Fix soft-float ldbl-128ibm atan2l signs of zero results (bug 16390)

[Joseph S. Myers]

This patch fixes bug 16390, incorrect signs of zero results from
ldbl-128ibm atan2l, soft-float only.  The problem is a longstanding
GCC bug with fabsl not being correct for signed zero for soft float,
and the fix is using -fno-builtin-fabsl as a workaround, as already
done for various other source files.  Tested powerpc-nofpu.

2014-01-03  Joseph Myers  <joseph@codesourcery.com>

	[BZ #16390]
	* sysdeps/powerpc/nofpu/Makefile [$(subdir) = math]
	(CFLAGS-e_atan2l.c): Use -fno-builtin-fabsl.

diff --git a/sysdeps/powerpc/nofpu/Makefile b/sysdeps/powerpc/nofpu/Makefile
index 9de7c43..99761ef 100644
--- a/sysdeps/powerpc/nofpu/Makefile
+++ b/sysdeps/powerpc/nofpu/Makefile
@@ -15,6 +15,7 @@ CPPFLAGS += -I../soft-fp/
 # gcc-4.1.1 and may be too late for gcc-4.2.  So we need these flags
 # until the fix in a gcc release and glibc drops support for earlier
 # versions of gcc.
+CFLAGS-e_atan2l.c += -fno-builtin-fabsl
 CFLAGS-e_hypotl.c += -fno-builtin-fabsl
 CFLAGS-e_powl.c += -fno-builtin-fabsl
 CFLAGS-s_ccoshl.c += -fno-builtin-fabsl

-- 
Joseph S. Myers
joseph@codesourcery.com