[i386][musl] Add cpuinfo to static libgcc only on *-musl*

The __cpu_indicator_init and __cpu_model symbols are not safe to use
from shared libgcc_s.so from ifunc resolvers, so since gcc-6, only
the definitions from static libgcc.a are used, however the symbols
are kept in libgcc_s as well for backward compatibility (with
appropriate symbol version).  On targets without such backward
compatibility concern add cpuinfo to the static library only (this
avoids running the ctor, reduces libgcc_s size and elf abi concerns
about the versioned symbols).

libgcc/
2016-11-11  Szabolcs Nagy  <szabolcs.nagy@arm.com>

	* config.host (i[3456]86-*-musl*, x86_64-*-musl*): Use
	i386/t-cpuinfo-static instead of i386/t-cpuinfo.
	* config/i386/t-cpuinfo-static: New.

From-SVN: r242268

libgcc/ChangeLog

+2016-11-11  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	* config.host (i[3456]86-*-musl*, x86_64-*-musl*): Use
+	i386/t-cpuinfo-static instead of i386/t-cpuinfo.
+	* config/i386/t-cpuinfo-static: New.
+
 2016-11-03  Martin Liska  <mliska@suse.cz>
 
 	* libgcov-profiler.c (__gcov_time_profiler): Remove.

libgcc/config.host

@@ -1320,7 +1320,14 @@ esac
 
 case ${host} in
 i[34567]86-*-* | x86_64-*-*)
-	tmake_file="${tmake_file} i386/t-cpuinfo"
+	case ${host} in
+	*-musl*)
+		tmake_file="${tmake_file} i386/t-cpuinfo-static"
+		;;
+	*)
+		tmake_file="${tmake_file} i386/t-cpuinfo"
+		;;
+	esac
 	;;
 esac
 

libgcc/config/i386/t-cpuinfo-static

+# If the compatibility cpuinfo symbols in shared libgcc_s are not needed
+# then they can be added to the static library only.
+
+LIB2ADD_ST += $(srcdir)/config/i386/cpuinfo.c