Expose rpath entries as a build variable

Unlike commit e2239cc, this only adds "." to the rpath if isNativeDeps is true.

--
PiperOrigin-RevId: 148330144
MOS_MIGRATED_REVID=148330144

Author: hlopko

src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java

@@ -403,12 +403,12 @@ protected CppConfiguration(CppConfigurationParameters params)
 
     this.toolchainIdentifier = toolchain.getToolchainIdentifier();
 
+    this.supportsEmbeddedRuntimes = toolchain.getSupportsEmbeddedRuntimes();
     toolchain = addLegacyFeatures(toolchain);
     this.toolchainFeatures = new CcToolchainFeatures(toolchain);
     this.supportsGoldLinker = toolchain.getSupportsGoldLinker();
     this.supportsStartEndLib = toolchain.getSupportsStartEndLib();
     this.supportsInterfaceSharedObjects = toolchain.getSupportsInterfaceSharedObjects();
-    this.supportsEmbeddedRuntimes = toolchain.getSupportsEmbeddedRuntimes();
     this.supportsFission = toolchain.getSupportsFission();
     this.toolchainNeedsPic = toolchain.getNeedsPic();
     this.usePicForBinaries =
@@ -727,12 +727,12 @@ private CToolchain addLegacyFeatures(CToolchain toolchain) {
           if (getTargetLibc().equals("macosx")) {
             TextFormat.merge(
                 CppLinkActionConfigs.getCppLinkActionConfigs(
-                    CppLinkPlatform.MAC, features, linkerToolPath),
+                    CppLinkPlatform.MAC, features, linkerToolPath, supportsEmbeddedRuntimes),
                 toolchainBuilder);
           } else {
             TextFormat.merge(
                 CppLinkActionConfigs.getCppLinkActionConfigs(
-                    CppLinkPlatform.LINUX, features, linkerToolPath),
+                    CppLinkPlatform.LINUX, features, linkerToolPath, supportsEmbeddedRuntimes),
                 toolchainBuilder);
           }
         }