Add crtbegin_so/crtend_so to Bionic Rust libraries.

Bug: 153430438
Test: Example library no longer experiences linkage errors during build.
Change-Id: I73870a68693415b37c9b7bf051b1879bcb8df0c6
diff --git a/rust/library.go b/rust/library.go
index 0cf2dd0..bf863bb 100644
--- a/rust/library.go
+++ b/rust/library.go
@@ -318,6 +318,8 @@
 
 	if ctx.toolchain().Bionic() && (library.dylib() || library.shared()) {
 		deps = library.baseCompiler.bionicDeps(ctx, deps)
+		deps.CrtBegin = "crtbegin_so"
+		deps.CrtEnd = "crtend_so"
 	}
 
 	return deps