LibC: Actually set the FPU environment instead of its pointer

Author: https://github.com/timschumi
Commit: 89f9454785
Pull-request: https://github.com/SerenityOS/serenity/pull/13838
Issue: https://github.com/SerenityOS/serenity/issues/13816

Userland/Libraries/LibC/fenv.cpp

@@ -72,7 +72,7 @@ int fesetenv(fenv_t const* env)
         return 0;
     }
 
-    asm volatile("fldenv %0" ::"m"(env)
+    asm volatile("fldenv %0" ::"m"(env->__x87_fpu_env)
                  : "memory");
 
     set_mxcsr(env->__mxcsr);