[compiler-rt] Enable GWP-ASan for Hexagon (#188410)

Add Hexagon to ALL_GWP_ASAN_SUPPORTED_ARCH, add struct layout
assertions.

GitOrigin-RevId: a33acdb0b2dca00db08630050b10b09a7546235a

common.h

diff --git a/common.h b/common.h
index df45102..5e33c6f 100644
--- a/common.h
+++ b/common.h
@@ -187,6 +187,11 @@
 static_assert(offsetof(AllocatorState, FailureAddress) == 28, "");
 static_assert(sizeof(AllocationMetadata) == 560, "");
 static_assert(offsetof(AllocationMetadata, IsDeallocated) == 552, "");
+#elif defined(__hexagon__)
+static_assert(sizeof(AllocatorState) == 32, "");
+static_assert(offsetof(AllocatorState, FailureAddress) == 28, "");
+static_assert(sizeof(AllocationMetadata) == 560, "");
+static_assert(offsetof(AllocationMetadata, IsDeallocated) == 552, "");
 #endif // defined($ARCHITECTURE)
 
 } // namespace gwp_asan