user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/options/ansi/musl-generic-math/nearbyintl.c

@@ -0,0 +1,26 @@
+#include <math.h>
+#include <float.h>
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double nearbyintl(long double x)
+{
+	return nearbyint(x);
+}
+#else
+#include <fenv.h>
+long double nearbyintl(long double x)
+{
+#ifdef FE_INEXACT
+	#pragma STDC FENV_ACCESS ON
+	int e;
+
+	e = fetestexcept(FE_INEXACT);
+#endif
+	x = rintl(x);
+#ifdef FE_INEXACT
+	if (!e)
+		feclearexcept(FE_INEXACT);
+#endif
+	return x;
+}
+#endif