Change Attribute.skipConstraintsCheck() (and similar methods)
to Attribute.skipPrereqValidatorCheck.

This is to disambiguate the concept of "constraints" and keep
the word consciously focused on Bazel's *new* constraint system.
The changed methods refer to checks done by PrerequisiteValidator,
which is basically an adhoc version of the "old" system (e.g.
checking visibility)

--
MOS_MIGRATED_REVID=103872412
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
index 4cdc269..10395cb 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
@@ -1578,7 +1578,7 @@
       validateDirectPrerequisiteType(prerequisite, attribute);
       validateDirectPrerequisiteFileTypes(prerequisite, attribute);
       validateMandatoryProviders(prerequisite, attribute);
-      if (attribute.performConstraintsCheck()) {
+      if (attribute.performPrereqValidatorCheck()) {
         prerequisiteValidator.validate(this, prerequisite, attribute);
       }
     }