Add ISO C99 complex support for doubles.

* include/complex.h: New file.
	* mingwex/complex: New directory.
	* mingwex/complex/cabs.c: New file.
	* mingwex/complex/cacos.c: New file.
	* mingwex/complex/cacosh.c: New file.
	* mingwex/complex/casin.c: New file.
	* mingwex/complex/casinh.c: New file.
	* mingwex/complex/catan.c: New file.
	* mingwex/complex/catanh.c: New file.
	* mingwex/complex/ccos.c: New file.
	* mingwex/complex/ccosh.c: New file.
	* mingwex/complex/cexp.c: New file.
	* mingwex/complex/cimag.c: New file.
	* mingwex/complex/clog.c: New file.
	* mingwex/complex/cpow.c: New file.
	* mingwex/complex/cproj.c: New file.
	* mingwex/complex/creal.c: New file.
	* mingwex/complex/csin.c: New file.
	* mingwex/complex/csinh.c: New file.
	* mingwex/complex/csqrt.c: New file.
	* mingwex/complex/ctan.c: New file.
	* mingwex/complex/ctanh.c: New file.
	* mingwex/Makefile.in (COMPLEX_DISTFILES): New list of
	files.
	(dist): Use it.
	(COMPLEX_OBJS): New list of objects.
	(LIB_OBJS): Include it in the library.

winsup/mingw/mingwex/complex/ctan.c

@@ -0,0 +1,41 @@
+/* ctan.c */
+
+/*
+   Contributed by Danny Smith
+   2003-10-20
+*/
+
+#include <math.h>
+#include <complex.h>
+#include <errno.h>
+
+
+/* ctan (x + I * y) = (sin (2 * x)  +  I * sinh(2 * y))
+		      / (cos (2 * x)  +  cosh (2 * y)) */
+
+double complex ctan (double complex Z)
+{
+  double complex Res;
+  double two_I = 2.0 * __imag__ Z;
+  double two_R = 2.0 * __real__ Z;
+  double denom = cos (two_R) + cosh (two_I);
+  if (denom == 0.0)
+    {
+      errno = ERANGE;
+      __real__ Res = HUGE_VAL;
+      __imag__ Res = HUGE_VAL;
+    }
+  else if (isinf (denom))
+    {
+      errno = ERANGE;
+      __real__ Res = 0.0;
+      __imag__ Res = two_I > 0 ? 1.0 : -1.0;
+    }
+  else
+    {
+      __real__ Res = sin (two_R) / denom;
+      __imag__ Res = sinh (two_I) / denom;
+    }
+  return Res;
+}
+