libgcc/gcc-runtime: Disable thumb mode on armv6

Without this the build fails for armv6t targets due to invalid
assembler instructions in thumb mode.

[YOCTO #12929]

(From OE-Core rev: 801141be68e5c754f2cd1d80d13982f037fc03e5)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/gcc/gcc-runtime_8.2.bb

@@ -8,3 +8,5 @@ FILES_libgomp-dev += "\
     ${libdir}/gcc/${TARGET_SYS}/${BINV}/include/openacc.h \
 "
 
+# Building with thumb enabled on armv6t fails
+ARM_INSTRUCTION_SET_armv6 = "arm"

meta/recipes-devtools/gcc/libgcc-initial_8.2.bb

@@ -1,2 +1,5 @@
 require recipes-devtools/gcc/gcc-${PV}.inc
 require libgcc-initial.inc
+
+# Building with thumb enabled on armv6t fails
+ARM_INSTRUCTION_SET_armv6 = "arm"

meta/recipes-devtools/gcc/libgcc_8.2.bb

@@ -1,2 +1,5 @@
 require recipes-devtools/gcc/gcc-${PV}.inc
 require libgcc.inc
+
+# Building with thumb enabled on armv6t fails
+ARM_INSTRUCTION_SET_armv6 = "arm"