[Serialization] Update env var to disable precise tag check

Rename the env var to SWIFT_IGNORE_SWIFTMODULE_REVISION as it's
recommended for use outside of testing.

Author: xymus

Diff for: lib/Serialization/ModuleFileSharedCore.cpp

@@ -356,7 +356,7 @@ static ValidationInfo validateControlBlock(
       // Disable this restriction for compiler testing by setting this
       // env var to any value.
       static const char* ignoreRevision =
-        ::getenv("SWIFT_DEBUG_IGNORE_SWIFTMODULE_REVISION");
+        ::getenv("SWIFT_IGNORE_SWIFTMODULE_REVISION");
       if (ignoreRevision)
         break;
 

Diff for: test/Serialization/restrict-swiftmodule-to-revision.swift

@@ -37,8 +37,8 @@ foo()
 // RUN:   not %target-swift-frontend -typecheck %t/ResilientClient.swift -swift-version 5 -I %t/build -parse-stdlib -module-cache-path %t/cache 2>&1 | %FileCheck %s
 // CHECK: compiled module was created by a different version of the compiler; rebuild 'ResilientLib' and try again: {{.*}}ResilientLib.swiftmodule
 
-/// Building a ResilientLib client should succeed for a tagged compiler with SWIFT_DEBUG_IGNORE_SWIFTMODULE_REVISION
-// RUN: env SWIFT_DEBUG_FORCE_SWIFTMODULE_REVISION=not-a-revision SWIFT_DEBUG_IGNORE_SWIFTMODULE_REVISION=true \
+/// Building a ResilientLib client should succeed for a tagged compiler with SWIFT_IGNORE_SWIFTMODULE_REVISION
+// RUN: env SWIFT_DEBUG_FORCE_SWIFTMODULE_REVISION=not-a-revision SWIFT_IGNORE_SWIFTMODULE_REVISION=true \
 // RUN:   %target-swift-frontend -typecheck %t/ResilientClient.swift -swift-version 5 -I %t/build -parse-stdlib -module-cache-path %t/cache