toolchain: Add GCC 9.1.0 release

Most of the patches are copied over from GCC 8.3.

The following patches are backported from the GCC 9.X development branch:
toolchain/gcc/patches/9.1.0/970-recompute-dom-fast-queries-before-vn.patch
toolchain/gcc/patches/9.1.0/975-g++-ICE-with-generic-lambda.patch

The specs file changed with gcc 9, now it contains "%@{L*}" instead of
"%{L*}" in older GCC versions.

Signed-off-by: Joseph Benden <joe@benden.us>

toolchain/gcc/patches/9.1.0/820-libgcc_pic.patch

@@ -0,0 +1,44 @@
+commit c96312958c0621e72c9b32da5bc224ffe2161384
+Author: Felix Fietkau <nbd@openwrt.org>
+Date:   Mon Oct 19 23:26:09 2009 +0000
+
+    gcc: create a proper libgcc_pic.a static library for relinking (4.3.3+ for now, backport will follow)
+    
+    SVN-Revision: 18086
+
+--- a/libgcc/Makefile.in
++++ b/libgcc/Makefile.in
+@@ -927,11 +927,12 @@ $(libgcov-driver-objects): %$(objext): $
+ 
+ # Static libraries.
+ libgcc.a: $(libgcc-objects)
++libgcc_pic.a: $(libgcc-s-objects)
+ libgcov.a: $(libgcov-objects)
+ libunwind.a: $(libunwind-objects)
+ libgcc_eh.a: $(libgcc-eh-objects)
+ 
+-libgcc.a libgcov.a libunwind.a libgcc_eh.a:
++libgcc.a libgcov.a libunwind.a libgcc_eh.a libgcc_pic.a:
+ 	-rm -f $@
+ 
+ 	objects="$(objects)";					\
+@@ -955,7 +956,7 @@ all: libunwind.a
+ endif
+ 
+ ifeq ($(enable_shared),yes)
+-all: libgcc_eh.a libgcc_s$(SHLIB_EXT)
++all: libgcc_eh.a libgcc_pic.a libgcc_s$(SHLIB_EXT)
+ ifneq ($(LIBUNWIND),)
+ all: libunwind$(SHLIB_EXT)
+ libgcc_s$(SHLIB_EXT): libunwind$(SHLIB_EXT)
+@@ -1161,6 +1162,10 @@ install-shared:
+ 	chmod 644 $(DESTDIR)$(inst_libdir)/libgcc_eh.a
+ 	$(RANLIB) $(DESTDIR)$(inst_libdir)/libgcc_eh.a
+ 
++	$(INSTALL_DATA) libgcc_pic.a $(mapfile) $(DESTDIR)$(inst_libdir)/
++	chmod 644 $(DESTDIR)$(inst_libdir)/libgcc_pic.a
++	$(RANLIB) $(DESTDIR)$(inst_libdir)/libgcc_pic.a
++
+ 	$(subst @multilib_dir@,$(MULTIDIR),$(subst \
+ 		@shlib_base_name@,libgcc_s,$(subst \
+ 		@shlib_slibdir_qual@,$(MULTIOSSUBDIR),$(SHLIB_INSTALL))))