user: implement mlibc as the libc, finally.

It's finally done..

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

user/include/mlibc/options/ansi/generic/complex/carg.c

@@ -0,0 +1,59 @@
+/* $NetBSD: carg.c,v 1.1 2007/08/20 16:01:31 drochner Exp $ */
+
+/*
+ * Written by Matthias Drochner <drochner@NetBSD.org>.
+ * Public domain.
+ *
+ * imported and modified include for newlib 2010/10/03 
+ * Marco Atzeri <marco_atzeri@yahoo.it>
+ */
+
+/*
+FUNCTION
+        <<carg>>, <<cargf>>---argument (phase angle)
+
+INDEX
+        carg
+INDEX
+        cargf
+
+SYNOPSIS
+       #include <complex.h>
+       double carg(double complex <[z]>);
+       float cargf(float complex <[z]>);
+
+
+DESCRIPTION
+        These functions compute the argument (also called phase angle) 
+        of <[z]>, with a branch cut along the negative real axis.
+
+        <<cargf>> is identical to <<carg>>, except that it performs
+        its calculations on <<floats complex>>.
+
+RETURNS
+        @ifnottex
+        The carg functions return the value of the argument in the 
+        interval [-pi, +pi]
+        @end ifnottex
+        @tex
+        The carg functions return the value of the argument in the 
+        interval [$-\pi$, $+\pi$]
+        @end tex
+
+PORTABILITY
+        <<carg>> and <<cargf>> are ISO C99
+
+QUICKREF
+        <<carg>> and <<cargf>> are ISO C99
+
+*/
+
+#include <complex.h>
+#include <math.h>
+
+double
+carg(double complex z)
+{
+
+	return atan2( cimag(z) , creal(z) );
+}