bp2build: convert paths/module refs to Bazel label

This currently expands all globs, still need to support converting glob
syntax.

Test: go build_conversion_test
Test: GENERATE_BAZEL_FILES=true m nothing
Test: m nothing
Bug: 165114590
Change-Id: If7b26e8e663d17566fad9614ca87a8da1f095284
diff --git a/cc/linker.go b/cc/linker.go
index ff07224..6d0d416 100644
--- a/cc/linker.go
+++ b/cc/linker.go
@@ -328,7 +328,9 @@
 		}
 
 		deps.SystemSharedLibs = linker.Properties.System_shared_libs
-		if deps.SystemSharedLibs == nil {
+		// In Bazel conversion mode, variations have not been specified, so SystemSharedLibs may
+		// inaccuarately appear unset, which can cause issues with circular dependencies.
+		if deps.SystemSharedLibs == nil && !ctx.BazelConversionMode() {
 			// Provide a default system_shared_libs if it is unspecified. Note: If an
 			// empty list [] is specified, it implies that the module declines the
 			// default system_shared_libs.