Remove -Wno-unknown-pragmas from fusl build

fusl/src/math/fmal.c

 /* origin: FreeBSD /usr/src/lib/msun/src/s_fmal.c */
 /*-
  * Copyright (c) 2005-2011 David Schultz <das@FreeBSD.ORG>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 146 matching lines @@
  * Fused multiply-add: Compute x * y + z with a single rounding error.
  *
  * We use scaling to avoid overflow/underflow, along with the
  * canonical precision-doubling technique adapted from:
  *
  *      Dekker, T.  A Floating-Point Technique for Extending the
  *      Available Precision.  Numer. Math. 18, 224-242 (1971).
  */
 long double fmal(long double x, long double y, long double z)
 {
-        #pragma STDC FENV_ACCESS ON
+        PRAGMA_STDC_FENV_ACCESS_ON
         long double xs, ys, zs, adj;
         struct dd xy, r;
         int oround;
         int ex, ey, ez;
         int spread;
 
         /*
          * Handle special cases. The order of operations and the particular
          * return values here are crucial in handling special cases involving
          * infinities, NaNs, overflows, and signed zeroes correctly.
@@ skipping 106 matching lines @@
                 return ret;
         }
 
         adj = add_adjusted(r.lo, xy.lo);
         if (spread + ilogbl(r.hi) > -16383)
                 return scalbnl(r.hi + adj, spread);
         else
                 return add_and_denormalize(r.hi, adj, spread);
 }
 #endif