Transformation for build configurations based on a platform/flags mapping.

Introduces a new SkyValue which stores the information obtained from a mapping file (parser yet to be written) and provides logic to transform a build configuration (key) based on that.

Step 3/N towards the platforms mapping functionality for https://github.com/bazelbuild/bazel/issues/6426

RELNOTES: None.
PiperOrigin-RevId: 238298127
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctions.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctions.java
index ea7724a..8bfa5df 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctions.java
@@ -21,9 +21,7 @@
 import com.google.devtools.build.skyframe.SkyFunctionName;
 import com.google.devtools.build.skyframe.SkyKey;
 
-/**
- * Value types in Skyframe.
- */
+/** Value types in Skyframe. */
 public final class SkyFunctions {
   public static final SkyFunctionName PRECOMPUTED =
       SkyFunctionName.createNonHermetic("PRECOMPUTED");
@@ -120,6 +118,8 @@
   public static final SkyFunctionName BUILD_INFO = SkyFunctionName.createHermetic("BUILD_INFO");
   public static final SkyFunctionName WORKSPACE_NAME =
       SkyFunctionName.createHermetic("WORKSPACE_NAME");
+  static final SkyFunctionName PLATFORM_MAPPING =
+      SkyFunctionName.createHermetic("PLATFORM_MAPPING");
   static final SkyFunctionName COVERAGE_REPORT = SkyFunctionName.createHermetic("COVERAGE_REPORT");
   public static final SkyFunctionName REPOSITORY = SkyFunctionName.createHermetic("REPOSITORY");
   public static final SkyFunctionName REPOSITORY_DIRECTORY =