Fix #4496

This commit revises legecy codegen to inserts a bkpt instruction if the current BB
and next BB is not in the same exception handling region.

This code is backported from ARM64 codegen.

src/jit/codegenlegacy.cpp

@@ -13243,6 +13243,9 @@ void                CodeGen::genCodeForBBlist()
 #if FEATURE_EH_FUNCLETS
                 || (block->bbNext->bbFlags & BBF_FUNCLET_BEG)
 #endif // FEATURE_EH_FUNCLETS
+#if defined(_TARGET_ARM_)
+                || !BasicBlock::sameEHRegion(block, block->bbNext)
+#endif
                 || (!isFramePointerUsed() && compiler->fgIsThrowHlpBlk(block->bbNext))
                 || block->bbNext == compiler->fgFirstColdBlock
                 )