rs6000: Link with libc128.a for long-double-128.

AIX applications using 128-bit long double must be linked with
libc128.a, in order to have 128-bit compatible routines.

AIX 7.2, 7.1, 6.1: Build/Tests: OK

2020-04-03 Clément Chigot <clement.chigot@atos.net>

* config/rs6000/aix61.h (LIB_SPEC): Add -lc128 with -mlong-double-128.
* config/rs6000/aix71.h (LIB_SPEC): Likewise.
* config/rs6000/aix72.h (LIB_SPEC): Likewise.

gcc/ChangeLog

+2020-04-08  Clement Chigot  <clement.chigot@atos.net>
+
+	* config/rs6000/aix61.h (LIB_SPEC): Add -lc128 with -mlong-double-128.
+	* config/rs6000/aix71.h (LIB_SPEC): Likewise.
+	* config/rs6000/aix72.h (LIB_SPEC): Likewise.
+
 2020-04-08  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/94526

gcc/config/rs6000/aix61.h

@@ -154,6 +154,7 @@ do {									\
    %{!maix64:%{!shared:%{g*:-lg}}}\
    %{fprofile-arcs|fprofile-generate*|coverage:-lpthreads}\
    %{mpe:-L%R/usr/lpp/ppe.poe/lib -lmpi -lvtd}\
+   %{mlong-double-128:-lc128}\
    %{pthread:-lpthreads} -lc"
 
 #undef LINK_SPEC

gcc/config/rs6000/aix71.h

@@ -162,6 +162,7 @@ do {									\
    %{!maix64:%{!shared:%{g*:-lg}}}\
    %{fprofile-arcs|fprofile-generate*|coverage:-lpthreads}\
    %{mpe:-L%R/usr/lpp/ppe.poe/lib -lmpi -lvtd}\
+   %{mlong-double-128:-lc128}\
    %{pthread:-lpthreads} -lc"
 
 #undef LINK_SPEC

gcc/config/rs6000/aix72.h

@@ -163,6 +163,7 @@ do {									\
    %{!maix64:%{!shared:%{g*:-lg}}}\
    %{fprofile-arcs|fprofile-generate*|coverage:-lpthreads}\
    %{mpe:-L%R/usr/lpp/ppe.poe/lib -lmpi -lvtd}\
+   %{mlong-double-128:-lc128}\
    %{pthread:-lpthreads} -lc"
 
 #undef LINK_SPEC