[builtins] Check __SEH__, when checking if ARM EHABI is implied

ARM EHABI isn't signalled by any specific compiler builtin define,
but is implied by the lack of defines specifying any other
exception handling mechanism, `__USING_SJLJ_EXCEPTIONS__` or
`__ARM_DWARF_EH__`.

As Windows SEH also can be used for unwinding, check for the
`__SEH__` define too, in the same way.

This is the same change as 4a3722a2c3 /
D126866, applied on the compiler-rt builtins gcc_personality_v0
function.

Differential Revision: https://reviews.llvm.org/D126863

compiler-rt/lib/builtins/gcc_personality_v0.c

@@ -143,7 +143,7 @@ static uintptr_t readEncodedPointer(const uint8_t **data, uint8_t encoding) {
 }
 
 #if defined(__arm__) && !defined(__USING_SJLJ_EXCEPTIONS__) &&                 \
-    !defined(__ARM_DWARF_EH__)
+    !defined(__ARM_DWARF_EH__) && !defined(__SEH__)
 #define USING_ARM_EHABI 1
 _Unwind_Reason_Code __gnu_unwind_frame(struct _Unwind_Exception *,
                                        struct _Unwind_Context *);