Description of problem: asterisk fails to build on ppc64, ppc64le and s390 with the following error message

powerpc:
--------
gcc -o chan_pjsip.o -c chan_pjsip.c -MD -MT chan_pjsip.o -MF .chan_pjsip.o.d -MP -pthread -I/builddir/build/BUILD/asterisk-13.7.1/include -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches  -m64 -mcpu=power7 -mtune=power8 -Werror-implicit-function-declaration -DLUA_COMPAT_MODULE -fsigned-char  -I/usr/include/libxml2 -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations      -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fPIC -DAST_MODULE=\"chan_pjsip\"     
In file included from /usr/include/pj/types.h:33:0,
                 from /usr/include/pjsip/sip_config.h:27,
                 from /usr/include/pjsip/sip_types.h:34,
                 from /usr/include/pjsip.h:24,
                 from chan_pjsip.c:37:
/usr/include/pj/config.h:290:6: error: #error Endianness must be declared for this processor
 #    error Endianness must be declared for this processor
      ^
In file included from /usr/include/pj/types.h:33:0,
                 from /usr/include/pjsip/sip_config.h:27,
                 from /usr/include/pjsip/sip_types.h:34,
                 from /usr/include/pjsip.h:24,
                 from chan_pjsip.c:37:
/usr/include/pj/config.h:1194:4: error: #error "PJ_IS_LITTLE_ENDIAN is not defined!"
 #  error "PJ_IS_LITTLE_ENDIAN is not defined!"
    ^
/usr/include/pj/config.h:1198:4: error: #error "PJ_IS_BIG_ENDIAN is not defined!"
 #  error "PJ_IS_BIG_ENDIAN is not defined!"
    ^
/builddir/build/BUILD/asterisk-13.7.1/Makefile.rules:143: recipe for target 'chan_pjsip.o' failed
make[1]: Leaving directory '/builddir/build/BUILD/asterisk-13.7.1/channels'
make[1]: *** [chan_pjsip.o] Error 1
make: *** [channels] Error 2

s390:
-----
gcc -o chan_pjsip.o -c chan_pjsip.c -MD -MT chan_pjsip.o -MF .chan_pjsip.o.d -MP -pthread -I/builddir/build/BUILD/asterisk-13.7.1/include -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m31 -march=z9-109 -mtune=z10 -Werror-implicit-function-declaration -DLUA_COMPAT_MODULE -fsigned-char  -I/usr/include/libxml2 -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations      -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fPIC -DAST_MODULE=\"chan_pjsip\"     
In file included from /usr/include/pj/types.h:33:0,
                 from /usr/include/pjsip/sip_config.h:27,
                 from /usr/include/pjsip/sip_types.h:34,
                 from /usr/include/pjsip.h:24,
                 from chan_pjsip.c:37:
/usr/include/pj/config.h:314:5: error: #error "Please specify target machine."
 #   error "Please specify target machine."
     ^
In file included from /usr/include/pj/types.h:33:0,
                 from /usr/include/pjsip/sip_config.h:27,
                 from /usr/include/pjsip/sip_types.h:34,
                 from /usr/include/pjsip.h:24,
                 from chan_pjsip.c:37:
/usr/include/pj/config.h:1204:4: error: #error "PJ_HAS_PENTIUM is not defined!"
 #  error "PJ_HAS_PENTIUM is not defined!"
    ^
/usr/include/pj/config.h:1208:4: error: #error "PJ_IS_LITTLE_ENDIAN is not defined!"
 #  error "PJ_IS_LITTLE_ENDIAN is not defined!"
    ^
/usr/include/pj/config.h:1212:4: error: #error "PJ_IS_BIG_ENDIAN is not defined!"
 #  error "PJ_IS_BIG_ENDIAN is not defined!"
    ^
/builddir/build/BUILD/asterisk-13.7.1/Makefile.rules:143: recipe for target 'chan_pjsip.o' failed
make[1]: Leaving directory '/builddir/build/BUILD/asterisk-13.7.1/channels'
Makefile:393: recipe for target 'channels' failed
make[1]: *** [chan_pjsip.o] Error 1
make: *** [channels] Error 2


Version-Release number of selected component (if applicable): 13.7.1-1


How reproducible: always on ppc-koji and s390-koji.