Add flag --experimental_enable_repo_mapping to gate usage of repo_mapping functionality in WORKSPACE rules.

RELNOTES: None
PiperOrigin-RevId: 199332092
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
index 1a5cc17..ac556e2 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
@@ -39,6 +39,8 @@
       AutoValue_SkylarkSemantics.class;
 
   // <== Add new options here in alphabetic order ==>
+  public abstract boolean experimentalEnableRepoMapping();
+
   public abstract boolean incompatibleBzlDisallowLoadAfterStatement();
 
   public abstract boolean incompatibleDepsetIsNotIterable();
@@ -86,6 +88,7 @@
   public static final SkylarkSemantics DEFAULT_SEMANTICS =
       builder()
           // <== Add new options here in alphabetic order ==>
+          .experimentalEnableRepoMapping(false)
           .incompatibleBzlDisallowLoadAfterStatement(false)
           .incompatibleDepsetIsNotIterable(false)
           .incompatibleDepsetUnion(false)
@@ -109,6 +112,8 @@
   public abstract static class Builder {
 
     // <== Add new options here in alphabetic order ==>
+    public abstract Builder experimentalEnableRepoMapping(boolean value);
+
     public abstract Builder incompatibleBzlDisallowLoadAfterStatement(boolean value);
 
     public abstract Builder incompatibleDepsetIsNotIterable(boolean value);