Patch GCC 4.7.4 for native musl support

Backport upstream patches to enable native musl toolchain support in
GCC. Only the changes required for i386 were taken, excluding
changes for libgo and libfortran.

These patches enable binaries built using gcc and g++ to automatically
use musl's dynamic linker as their interpreter when present during the
build.

sysc/gcc-4.7.4/patches/0002-fixincludes-update-for-musl-support.patch

@@ -0,0 +1,27 @@
+SPDX-FileCopyrightText: 2022 Dor Askayo <dor.askayo@gmail.com>
+SPDX-FileCopyrightText: 2015 Gregor Richards <gregor.richards@uwaterloo.ca>
+
+SPDX-License-Identifier: GPL-2.0-or-later
+
+Backported from upstream commit 218213dfd01e22b7c9f1be3119e32d970fa348bf
+
+fixincludes update for musl support
+
+2015-04-22  Gregor Richards  <gregor.richards@uwaterloo.ca>
+
+	* mkfixinc.sh: Add *-musl* with no fixes.
+
+From-SVN: r222327
+
+--- fixincludes/mkfixinc.sh
++++ fixincludes/mkfixinc.sh
+@@ -20,7 +20,8 @@ case $machine in
+     powerpc-*-eabi*    | \
+     powerpc-*-rtems*   | \
+     powerpcle-*-eabisim* | \
+-    powerpcle-*-eabi* )
++    powerpcle-*-eabi* | \
++    *-musl* )
+ 	#  IF there is no include fixing,
+ 	#  THEN create a no-op fixer and exit
+ 	(echo "#! /bin/sh" ; echo "exit 0" ) > ${target}