It seems to be libtool that's dropping the -specs option:

/usr/bin/libtool --mode=link gcc  -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -mcet -fcf-protection  -D_REENTRANT -Wl,-z,relro  -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -o libglib.la -rpath /usr/lib64 -version-info 0:10:0 -release 1.2 -export-dynamic garray.lo gcache.lo gcompletion.lo gdataset.lo gdate.lo gerror.lo ghash.lo ghook.lo giochannel.lo giounix.lo glist.lo gmain.lo gmem.lo gmessages.lo gmutex.lo gnode.lo gprimes.lo grel.lo gscanner.lo gslist.lo gstrfuncs.lo gstring.lo gtimer.lo gtree.lo gutils.lo
libtool: link: gcc -shared  -fPIC -DPIC  .libs/garray.o .libs/gcache.o .libs/gcompletion.o .libs/gdataset.o .libs/gdate.o .libs/gerror.o .libs/ghash.o .libs/ghook.o .libs/giochannel.o .libs/giounix.o .libs/glist.o .libs/gmain.o .libs/gmem.o .libs/gmessages.o .libs/gmutex.o .libs/gnode.o .libs/gprimes.o .libs/grel.o .libs/gscanner.o .libs/gslist.o .libs/gstrfuncs.o .libs/gstring.o .libs/gtimer.o .libs/gtree.o .libs/gutils.o    -O2 -g -fstack-protector-strong -grecord-gcc-switches -m64 -mtune=generic -mcet -Wl,-z -Wl,relro   -Wl,-soname -Wl,libglib-1.2.so.0 -o .libs/libglib-1.2.so.0.0.10

Any idea how to get libtool to pass -specs to gcc?

I should mention that this is an ancient package so I use the system libtool rather than the one shipped with the original source, which may be a related thing.

(In reply to Paul Howarth from comment #1)
> Any idea how to get libtool to pass -specs to gcc?

I asked about this recently here:

https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/FILPDYHXHOUOYFP65PS7SJNH5OD4RBUS/

I do not know yet how this is supposed to work.

This bug appears to have been reported against 'rawhide' during the Fedora 29 development cycle.
Changing version to '29'.

This bug appears to have been reported against 'rawhide' during the Fedora 32 development cycle.
Changing version to 32.

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This bug appears to have been reported against 'rawhide' during the Fedora 35 development cycle.
Changing version to 35.

Seems to be working now:
(https://kojipkgs.fedoraproject.org/packages/glib/1.2.10/64.fc36/data/logs/x86_64/build.log)

/usr/bin/libtool --mode=link gcc  -O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -m64  -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection  -D_REENTRANT -Wl,-z,relro -Wl,--as-needed  -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -Wl,--build-id=sha1 -Wl,-dT,/builddir/build/BUILD/.package_note-glib-1.2.10-64.fc36.x86_64.ld -o libglib.la -rpath /usr/lib64 -version-info 0:10:0 -release 1.2 -export-dynamic garray.lo gcache.lo gcompletion.lo gdataset.lo gdate.lo gerror.lo ghash.lo ghook.lo giochannel.lo giounix.lo glist.lo gmain.lo gmem.lo gmessages.lo gmutex.lo gnode.lo gprimes.lo grel.lo gscanner.lo gslist.lo gstrfuncs.lo gstring.lo gtimer.lo gtree.lo gutils.lo  
libtool: link: gcc -shared  -fPIC -DPIC  .libs/garray.o .libs/gcache.o .libs/gcompletion.o .libs/gdataset.o .libs/gdate.o .libs/gerror.o .libs/ghash.o .libs/ghook.o .libs/giochannel.o .libs/giounix.o .libs/glist.o .libs/gmain.o .libs/gmem.o .libs/gmessages.o .libs/gmutex.o .libs/gnode.o .libs/gprimes.o .libs/grel.o .libs/gscanner.o .libs/gslist.o .libs/gstrfuncs.o .libs/gstring.o .libs/gtimer.o .libs/gtree.o .libs/gutils.o    -O2 -flto=auto -g -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -Wl,-z -Wl,relro -Wl,--as-needed -Wl,-z -Wl,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1 -Wl,-dT -Wl,/builddir/build/BUILD/.package_note-glib-1.2.10-64.fc36.x86_64.ld   -Wl,-soname -Wl,libglib-1.2.so.0 -o .libs/libglib-1.2.so.0.0.10

This message is a reminder that Fedora Linux 35 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora Linux 35 on 2022-12-13.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
'version' of '35'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, change the 'version' 
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