[hwasan] Increase BB to explore for reachability

We pass mcpu=cortex-a55 for our build, which increases BB to the point
where the LLVM default of 32 is not enough. This caused worse coverage
for use-after-scope detection, and increased stack usage.

Test: build oriole_hwasan
Bug: 229654778
Change-Id: I6ddb47d7224a9c6ddbf2641c043e3430d330c5a9

cc/sanitize.go

@@ -61,6 +61,7 @@ var (
 		"--aarch64-enable-global-isel-at-O=-1",
 		"-fast-isel=false",
 		"-hwasan-use-after-scope=1",
+		"-dom-tree-reachability-max-bbs-to-explore=128",
 	}
 
 	cfiBlocklistPath     = "external/compiler-rt/lib/cfi"