[PATCH, committed] TILE-Gx: Use CXX_FOR_BUILD to compile c++ source.

[Walter Lee]

This patch uses g++ instead of gcc to compile a c++ source file. The GNU 
buildbot is currently failing with a c++ related link error that I have 
not been able to reproduce; I'm hoping using g++ will fix the issue.

2016-02-12  Walter Lee  <walt@tilera.com>

         * config/tilepro/t-tilepro: Replace CC_FOR_BUILD with
           CXX_FOR_BUILD.
         * config/tilegx/t-tilegx: Likewise.

Index: gcc/config/tilegx/t-tilegx
===================================================================
--- gcc/config/tilegx/t-tilegx    (revision 233352)
+++ gcc/config/tilegx/t-tilegx    (working copy)
@@ -12,7 +12,7 @@ tilegx-c.o: $(srcdir)/config/tilegx/tile

  $(srcdir)/config/tilegx/mul-tables.c: \
      $(srcdir)/config/tilepro/gen-mul-tables.cc
-    $(CC_FOR_BUILD) $(BUILD_CPPFLAGS) -O2 -o gen-mul-tables -lstdc++ $<;
+    $(CXX_FOR_BUILD) $(BUILD_CPPFLAGS) -O2 -o gen-mul-tables $<;
      ./gen-mul-tables > $@

  mul-tables.o: $(srcdir)/config/tilegx/mul-tables.c \
Index: gcc/config/tilepro/t-tilepro
===================================================================
--- gcc/config/tilepro/t-tilepro    (revision 233352)
+++ gcc/config/tilepro/t-tilepro    (working copy)
@@ -5,8 +5,8 @@ tilepro-c.o: $(srcdir)/config/tilepro/ti

  $(srcdir)/config/tilepro/mul-tables.c: \
      $(srcdir)/config/tilepro/gen-mul-tables.cc
-    $(CC_FOR_BUILD) $(BUILD_CPPFLAGS) -O2 -DTILEPRO \
-      -o gen-mul-tables -lstdc++ $<;
+    $(CXX_FOR_BUILD) $(BUILD_CPPFLAGS) -O2 -DTILEPRO \
+      -o gen-mul-tables $<;
      ./gen-mul-tables > $@