Harden CrasherTest::Trap under sanitizers.

The use of __builtin_abort in CrasherTest::Trap breaks with
-ftrap-function=abort, because then the argument of Trap is no longer in
the first argument register at the time of crash.

This flag is added when *any* sanitizer is enabled on the target, even harmless
ones like memtag-heap. See sanitize.go:769.

Fix CrasherTest::Trap to be a little more reliable.

Test: debuggerd_test with SANITIZE_TARGET=memtag_heap
Change-Id: I150f1c0355bd6f2bfabfa5a7bba125acdde1120e
diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index aca476f..c08721b 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -406,10 +406,10 @@
       result, R"(signal 11 \(SIGSEGV\), code 1 \(SEGV_MAPERR\), fault addr 0x[01]00000000000dead)");
 }
 
-// Marked as weak to prevent the compiler from removing the malloc in the caller. In theory, the
-// compiler could still clobber the argument register before trapping, but that's unlikely.
-__attribute__((weak)) void CrasherTest::Trap(void* ptr ATTRIBUTE_UNUSED) {
-  __builtin_trap();
+void CrasherTest::Trap(void* ptr) {
+  void (*volatile f)(void*) = nullptr;
+  __asm__ __volatile__("" : : "r"(f) : "memory");
+  f(ptr);
 }
 
 TEST_F(CrasherTest, heap_addr_in_register) {
@@ -828,7 +828,7 @@
 
   StartIntercept(&output_fd);
   FinishCrasher();
-  AssertDeath(SIGTRAP);
+  AssertDeath(SIGSEGV);
   FinishIntercept(&intercept_result);
 
   ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";