gcc: add old patches for csky/nios2

toolchain/gcc/patches/13.2.0/csky.patch

@@ -0,0 +1,12 @@
+diff -Nur gcc-11.2.0.orig/libgcc/config/csky/linux-atomic.c gcc-11.2.0/libgcc/config/csky/linux-atomic.c
+--- gcc-11.2.0.orig/libgcc/config/csky/linux-atomic.c	2021-07-28 08:55:08.760307899 +0200
++++ gcc-11.2.0/libgcc/config/csky/linux-atomic.c	2021-12-14 14:19:23.685729233 +0100
+@@ -24,7 +24,7 @@
+    <http://www.gnu.org/licenses/>.	 */
+ 
+ /* Kernel helper for compare-and-exchange.  */
+-inline int
++int
+ __kernel_cmpxchg (int oldval, int newval, volatile int *ptr)
+ {
+   register int _a0 asm ("a0") = oldval;

toolchain/gcc/patches/13.2.0/nios2-softfp.patch

@@ -0,0 +1,14 @@
+diff -Nur gcc-6.2.0.orig/libgcc/config.host gcc-6.2.0/libgcc/config.host
+--- gcc-6.2.0.orig/libgcc/config.host	2016-05-17 08:15:52.000000000 +0200
++++ gcc-6.2.0/libgcc/config.host	2016-10-15 14:42:53.971919904 +0200
+@@ -962,6 +962,10 @@
+ 		;;
+ 	esac
+ 	;;
++nios2-*-linux-uclibc*)
++	tmake_file="$tmake_file nios2/t-nios2 nios2/t-linux t-libgcc-pic t-slibgcc-libgcc t-softfp-sfdf t-softfp"
++	md_unwind_header=nios2/linux-unwind.h
++	;;
+ nios2-*-linux*)
+ 	tmake_file="$tmake_file nios2/t-nios2 nios2/t-linux t-libgcc-pic t-slibgcc-libgcc"
+ 	md_unwind_header=nios2/linux-unwind.h