Export rust flags to bazel

Bug: 290790800
Test: Inspect out/soong/soong_inspection folder after running `m bp2build`
Change-Id: Iffc43a540f67e5f07d109a0a87f3248fae035267

rust/compiler.go

@@ -330,14 +330,7 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags) Flag
 	if ctx.Os() == android.Linux {
 		// Add -lc, -lrt, -ldl, -lpthread, -lm and -lgcc_s to glibc builds to match
 		// the default behavior of device builds.
-		flags.LinkFlags = append(flags.LinkFlags,
-			"-lc",
-			"-lrt",
-			"-ldl",
-			"-lpthread",
-			"-lm",
-			"-lgcc_s",
-		)
+		flags.LinkFlags = append(flags.LinkFlags, config.LinuxHostGlobalLinkFlags...)
 	} else if ctx.Os() == android.Darwin {
 		// Add -lc, -ldl, -lpthread and -lm to glibc darwin builds to match the default
 		// behavior of device builds.

rust/config/global.go

@@ -52,11 +52,22 @@ var (
 		"-C force-unwind-tables=yes",
 		// Use v0 mangling to distinguish from C++ symbols
 		"-C symbol-mangling-version=v0",
-		"--color always",
+		// This flag requires to have no space so that when it's exported to bazel
+		// it can be removed. See aosp/2768339
+		"--color=always",
 		"-Zdylib-lto",
 		"-Z link-native-libraries=no",
 	}
 
+	LinuxHostGlobalLinkFlags = []string{
+		"-lc",
+		"-lrt",
+		"-ldl",
+		"-lpthread",
+		"-lm",
+		"-lgcc_s",
+	}
+
 	deviceGlobalRustFlags = []string{
 		"-C panic=abort",
 		// Generate additional debug info for AutoFDO
@@ -101,6 +112,8 @@ func init() {
 	pctx.StaticVariable("DeviceGlobalLinkFlags", strings.Join(deviceGlobalLinkFlags, " "))
 
 	exportedVars.ExportStringStaticVariable("RUST_DEFAULT_VERSION", RustDefaultVersion)
+	exportedVars.ExportStringListStaticVariable("GLOBAL_RUSTC_FLAGS", GlobalRustFlags)
+	exportedVars.ExportStringListStaticVariable("LINUX_HOST_GLOBAL_LINK_FLAGS", LinuxHostGlobalLinkFlags)
 }
 
 func HostPrebuiltTag(config android.Config) string {