pcp fails to build with gcc 10:

gcc -Wl,-z,relro -Wl,--as-needed  -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wl,-z,relro -Wl,--as-needed  -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wall -L./src/libpcp/src -L./src/libpcp_web/src -L./src/libpcp_pmda/src  -Wl,-z,relro -Wl,--as-needed  -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wall -L../src/libpcp/src -L../src/libpcp_web/src -L../src/libpcp_pmda/src  -Wl,-z,relro -Wl,--as-needed  -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wall -L../../src/libpcp/src -L../../src/libpcp_web/src -L../../src/libpcp_pmda/src  -Wl,-z,relro -Wl,--as-needed  -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wall -L../../../src/libpcp/src -L../../../src/libpcp_web/src -L../../../src/libpcp_pmda/src  -shared -Wl,-soname,libpcp_web.so.1 -Wl,--version-script=exports -o libpcp_web.so.1  jsmn.o http_client.o http_parser.o sds.o siphash.o query.o schema.o load.o crc16.o sha1.o util.o slots.o redis.o net.o dict.o ini.o maps.o batons.o encoding.o json_helpers.o config.o libuv.o discover.o webgroup.o sslio.o     query_parser.tab.o -lssl -lcrypto  -luv -lrt -lpthread -ldl  -lpcp_pmda -lpcp -lm -luv -lrt -lpthread -ldl  -lssl -lcrypto   -ldl 
/usr/bin/ld: query.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: schema.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: load.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: util.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: slots.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: redis.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: net.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: maps.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: encoding.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: config.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: libuv.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: discover.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: webgroup.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: sslio.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
/usr/bin/ld: query_parser.tab.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: multiple definition of `SDS_NOINIT'; sds.o:/builddir/build/BUILD/pcp-5.0.2/src/libpcp_web/src/../../../src/include/pcp/sds.h:37: first defined here
collect2: error: ld returned 1 exit status


This blocks the Python 3.9 rebuild of the package.

See https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/RYVPP45PMWPXYBBDKXO3CI7YGL7CDQG6/ and https://gcc.gnu.org/gcc-10/porting_to.html#common for more information about the failure.