Restore libgcc_s symlinkin in !macOS (#47986)

Commit c8b72e2 completely removed libgcc_s symlinking (I assume unintentionally) in !macOS.

(cherry picked from commit ea13810)

Author: antonio-rojas

base/Makefile

@@ -231,6 +231,8 @@ else
 $(eval $(call symlink_system_library,CSL,libgcc_s,1))
 endif
 endif
+else
+$(eval $(call symlink_system_library,CSL,libgcc_s,1))
 endif
 ifneq (,$(LIBGFORTRAN_VERSION))
 $(eval $(call symlink_system_library,CSL,libgfortran,$(LIBGFORTRAN_VERSION)))