Based on the following commit, but modified for rhel-7.9.

commit c10acd40262486dac597001aecc20ad9d3bd0e4a
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Feb 13 17:01:15 2020 +0100

    math/test-sinl-pseudo: Use stack protector only if available
    
    This fixes commit 9333498794cde1d5cca518bad ("Avoid ldbl-96 stack
    corruption from range reduction of pseudo-zero (bug 25487).").

diff -urN a/sysdeps/ieee754/ldbl-96/Makefile b/sysdeps/ieee754/ldbl-96/Makefile
--- a/sysdeps/ieee754/ldbl-96/Makefile	2021-01-06 20:55:49.163141757 -0500
+++ b/sysdeps/ieee754/ldbl-96/Makefile	2021-01-06 20:58:06.612989216 -0500
@@ -18,5 +18,7 @@
 
 ifeq ($(subdir),math)
 tests += test-sinl-pseudo
+ifeq ($(have-ssp),yes)
 CFLAGS-test-sinl-pseudo.c += -fstack-protector-all
 endif
+endif # $(subdir) == math