sys-libs/glibc: use -mno-sdata, not -fcommon, bug #723268

-fcommon generated PLT references and added double memory
dereference.

-mno-sdata is slightly more efficient as it still sees
globals to be module local varilables and uses GPREL64
(instead of PLT indirection) and uses single memory
dereference.

Bug: https://bugs.gentoo.org/723268
Package-Manager: Portage-2.3.99, Repoman-2.3.22
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

sys-libs/glibc/glibc-2.30-r8.ebuild

@@ -309,7 +309,8 @@ setup_target_flags() {
 			# Workaround GPREL22 overflow by slightly pessimizing global
 			# references to go via 64-bit relocations instead of 22-bit ones.
 			# This allows building glibc on ia64 without an overflow: #723268
-			append-flags -fcommon
+			append-flags -mno-sdata
+			:
 		;;
 		mips)
 			# The mips abi cannot support the GNU style hashes. #233233

sys-libs/glibc/glibc-2.31-r3.ebuild

@@ -303,7 +303,8 @@ setup_target_flags() {
 			# Workaround GPREL22 overflow by slightly pessimizing global
 			# references to go via 64-bit relocations instead of 22-bit ones.
 			# This allows building glibc on ia64 without an overflow: #723268
-			append-flags -fcommon
+			append-flags -mno-sdata
+			:
 		;;
 		mips)
 			# The mips abi cannot support the GNU style hashes. #233233

sys-libs/glibc/glibc-9999.ebuild

@@ -302,7 +302,8 @@ setup_target_flags() {
 			# Workaround GPREL22 overflow by slightly pessimizing global
 			# references to go via 64-bit relocations instead of 22-bit ones.
 			# This allows building glibc on ia64 without an overflow: #723268
-			append-flags -fcommon
+			append-flags -mno-sdata
+			:
 		;;
 		mips)
 			# The mips abi cannot support the GNU style hashes. #233233