[PATCH] math: Fix `unknown type name '__float128'` for clang 3.4 to 3.8.1 (bug 32694)

[koraynilay]

When compiling a program that includes <bits/floatn.h> using a clang version
between 3.4 (included) and 3.8.1 (included), clang will fail with `unknown type
name '__float128'; did you mean '__cfloat128'?`. This changes fixes the clang
prerequirements macro call in floatn.h to check for clang 3.9 instead of 3.4,
since support for __float128 was actually enabled in 3.9 (see commit 50f29e0
of the llvm-project on github)

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: koraynilay <koray.fra@gmail.com>
---
 sysdeps/x86/bits/floatn.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sysdeps/x86/bits/floatn.h b/sysdeps/x86/bits/floatn.h
index adc7ed2e9e..4674165bd7 100644
--- a/sysdeps/x86/bits/floatn.h
+++ b/sysdeps/x86/bits/floatn.h
@@ -31,7 +31,7 @@
 #if (defined __x86_64__							\
      ? __GNUC_PREREQ (4, 3)						\
      : (defined __GNU__ ? __GNUC_PREREQ (4, 5) : __GNUC_PREREQ (4, 4))) \
-    || (__glibc_clang_prereq (3, 4)					\
+    || (__glibc_clang_prereq (3, 9)					\
 	&& (!defined __INTEL_LLVM_COMPILER				\
 	    || !defined SYCL_LANGUAGE_VERSION))
 # define __HAVE_FLOAT128 1
@@ -93,7 +93,7 @@ typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
 /* The type _Float128 exists only since GCC 7.0.  */
 #  if !__GNUC_PREREQ (7, 0) \
       || (defined __cplusplus && !__GNUC_PREREQ (13, 0)) \
-      || __glibc_clang_prereq (3, 4)
+      || __glibc_clang_prereq (3, 9)
 typedef __float128 _Float128;
 #  endif
 
-- 
2.48.1