AP_Common: check for feenableexcept on WAF

libraries/AP_Common/missing/fenv.h

@@ -2,6 +2,7 @@
 
 #include_next <fenv.h>
 
+#ifndef HAVE_FEENABLEEXCEPT
 #if defined(__APPLE__) && defined(__MACH__)
 
 // Public domain polyfill for feenableexcept on OS X
@@ -45,4 +46,29 @@ inline int fedisableexcept(unsigned int excepts)
     return fesetenv(&fenv) ? -1 : old_excepts;
 }
 
+#else
+inline int feenableexcept(unsigned int excepts)
+{
+    #pragma STDC FENV_ACCESS ON
+    fexcept_t flags;
+    /* Save current exception flags. */
+    fegetexceptflag(&flags, FE_ALL_EXCEPT);
+
+    feclearexcept(FE_ALL_EXCEPT);   /* clear all fp exception conditions */
+    return fesetexceptflag(&flags, excepts) != 0 ? -1 : flags; /* set new flags */
+
+}
+
+inline int fedisableexcept(unsigned int excepts)
+{
+    #pragma STDC FENV_ACCESS ON
+    fexcept_t flags;
+    /* Save current exception flags. */
+    fegetexceptflag(&flags, FE_ALL_EXCEPT);
+
+    feclearexcept(FE_ALL_EXCEPT);   /* clear all fp exception conditions */
+    return fesetexceptflag(&flags, ~excepts) != 0 ? -1 : flags; /* set new flags */
+}
+
+#endif
 #endif