gcc-sanitizers: don't use thumb for armv[45]

* otherwise it fails with:
sanitizer_linux.s:5749: Error: lo register required -- `ldr ip,[sp],#8'

@ 1538 "../../../../../../../../../work-shared/gcc-8.1.0-r0/gcc-8.1.0/libsanitizer/sanitizer_common/sanitizer_linux.cc" 1

        swi 0x0

cmp r0, #0
bne 1f
ldr r0, [sp, #4]
ldr ip, [sp], #8
blx ip
mov r7, #1
swi 0x0
1:
mov r0, r0

---
 meta/recipes-devtools/gcc/gcc-sanitizers_8.1.bb | 5 +++++
 1 file changed, 5 insertions(+)

index 601f666023..f3c7058114 100644
@@ -1,2 +1,7 @@
 require recipes-devtools/gcc/gcc-${PV}.inc
 require gcc-sanitizers.inc
+
+# Building with thumb enabled on armv4t armv5t fails with
+# sanitizer_linux.s:5749: Error: lo register required -- `ldr ip,[sp],#8'
+ARM_INSTRUCTION_SET_armv4 = "arm"
+ARM_INSTRUCTION_SET_armv5 = "arm"

2.17.0