Turn off Global ThinLTO for LP32 again

LP32 has many subtle issues and less test coverage.

Bug: 290859519
Bug: 169004486
Test: presubmit
Change-Id: I33fcf1a08b9e7a905ba81030250a9578532da5a0
diff --git a/cc/lto.go b/cc/lto.go
index e334af9..44361db 100644
--- a/cc/lto.go
+++ b/cc/lto.go
@@ -74,6 +74,9 @@
 	} else if ctx.Host() {
 		// Performance and binary size are less important for host binaries.
 		ltoDefault = false
+	} else if ctx.Arch().ArchType.Multilib == "lib32" {
+		// LP32 has many subtle issues and less test coverage.
+		ltoDefault = false
 	}
 
 	// Then, determine the actual LTO mode to use. If different from `ltoDefault`, a variant needs