StdLib: Patches and updates for ARM.

Add ARMGCC and RVCT toolchain support.
Update and Add ARM specific machine headers.
Set the empty macro for __warn_references().
Make __flt_rounds() return 'Round to nearest' by default on ARM.

Signed-off-by:  Olivier Martin [olivier.martin@arm.com]
Reviewed-by:    darylm503


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12367 6f19259b-4bc3-4df7-8a09-765794883524

StdLib/Include/Arm/machine/endian_machdep.h

@@ -0,0 +1,8 @@
+/* $NetBSD: endian_machdep.h,v 1.8 2006/01/30 21:52:38 dsl Exp $ */
+
+/* GCC predefines __ARMEB__ when building for big-endian ARM. */
+#ifdef __ARMEB__
+#define _BYTE_ORDER _BIG_ENDIAN
+#else
+#define _BYTE_ORDER _LITTLE_ENDIAN
+#endif