Remove spurious trailing backslash in prefer_rlib docstring

Change-Id: I851306c73cb86df4bc4c82c3471ce3b6eaad9ded

rust/compiler.go

@@ -161,7 +161,7 @@ type BaseCompilerProperties struct {
 	// This is primarily meant for rust_binary and rust_ffi modules where the default
 	// linkage of libstd might need to be overridden in some use cases. This should
 	// generally be avoided with other module types since it may cause collisions at
-	// linkage if all dependencies of the root binary module do not link against libstd\
+	// linkage if all dependencies of the root binary module do not link against libstd
 	// the same way.
 	Prefer_rlib *bool `android:"arch_variant"`