Disable fp exceptions in H5T init code

The floating-point datatype initialization code can generate
floating-point exceptions when it trips over signalling NaNs.

The easiest fix for this is to ignore FE_INVALID exceptions while
initializing the floating-point types.

src/H5Tinit_float.c

@@ -461,10 +461,17 @@ H5T__init_native_float_types(void)
 {
     H5T_fpoint_det_t det;
     H5T_t           *dt        = NULL;
+    int              fpe_flags = 0;
     herr_t           ret_value = SUCCEED;
 
     FUNC_ENTER_PACKAGE
 
+    /* Turn off floating-point exceptions while initializing to avoid
+     * tripping over signalling NaNs while looking at "don't care" bits.
+     */
+    fpe_flags = fegetexcept();
+    fedisableexcept(FE_INVALID);
+
     /* H5T_NATIVE_FLOAT */
 
     /* Get the type's characteristics */
@@ -564,6 +571,9 @@ H5T__init_native_float_types(void)
     H5T_native_order_g = det.order;
 
 done:
+    /* Restore the original exceptions */
+    feenableexcept(fpe_flags);
+
     if (ret_value < 0) {
         if (dt != NULL) {
             dt->shared = H5FL_FREE(H5T_shared_t, dt->shared);

src/H5private.h

@@ -26,6 +26,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <fenv.h>
 #include <float.h>
 #include <math.h>
 #include <setjmp.h>