Handle narrowing function sNaN test disabling based on argument format.

Testing narrowing functions for x86_64 with GCC 6 showed up a further
testsuite fix needed: there is no _Float128 sNaN support before GCC 7
on x86_64 / x86, and the existing tests of SNAN_TESTS only checked it
for the return type, not for the argument type.  This patch fixes the
code to check SNAN_TESTS (ARG_FLOAT) as well (in a variable set in
libm-test-driver.c, since libm-test-support.c is compiled only once
for each choice of FLOAT).

Tested for x86_64 and x86 with GCC 6 in conjunction with the main
patch adding narrowing add functions.

	* math/libm-test-driver.c (snan_tests_arg): New variable.
	* math/libm-test-support.h (snan_tests_arg): New declaration.
	* math/libm-test-support.c (enable_test): Check snan_tests_arg.

1 files changed, 6 insertions, 0 deletions

diff --git a/math/libm-test-driver.c b/math/libm-test-driver.c
index 3713e7074f..30646da862 100644
--- a/math/libm-test-driver.c
+++ b/math/libm-test-driver.c
@@ -27,6 +27,12 @@ const int flag_test_finite = TEST_FINITE;
 const int flag_test_inline = TEST_INLINE;
 const int flag_test_mathvec = TEST_MATHVEC;
 
+#if TEST_NARROW
+const int snan_tests_arg = SNAN_TESTS (ARG_FLOAT);
+#else
+const int snan_tests_arg = SNAN_TESTS (FLOAT);
+#endif
+
 #define STRX(x) #x
 #define STR(x) STRX (x)
 #define STR_FLOAT STR (FLOAT)