math: support platforms with limited FP rounding or exception support

For some tests, just claim that fetestexcept() always returns true,
so the rest of the test can be compiled.

For libm-test, provide known bogus values for unsupported rounding
modes, so fesetround() will return failure.

Elsewhere, just add some #ifdefs to avoid code that uses particular
FP exceptions if the exceptions aren't supported.

1 files changed, 6 insertions, 0 deletions

diff --git a/math/bug-nexttoward.c b/math/bug-nexttoward.c
index ff57e5e3f5..cedb7767b6 100644
--- a/math/bug-nexttoward.c
+++ b/math/bug-nexttoward.c
@@ -4,6 +4,12 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+#if !defined(FE_OVERFLOW) && !defined(FE_UNDERFLOW)
+/* If there's no support for the exceptions this test is checking,
+   then just return success and allow the test to be compiled.  */
+# define fetestexcept(e) 1
+#endif
+
 float zero = 0.0;
 float inf = INFINITY;