Revert "THRIFT-1907 Compiling namespace and sub-namespace directives for unrecognized generators should only be a warning"

This reverts commit d28d4d578470233e384ae6012d0ecfa5a8f3deba.
diff --git a/test/ThriftTest.thrift b/test/ThriftTest.thrift
index be000b6..2be53fa 100644
--- a/test/ThriftTest.thrift
+++ b/test/ThriftTest.thrift
@@ -35,12 +35,6 @@
 namespace php ThriftTest
 namespace delphi Thrift.Test
 namespace cocoa ThriftTest
-
-// Presence of namespaces and sub-namespaces for which there is
-// no generator should compile with warnings only
-namespace noexist ThriftTest
-namespace cpp.noexist ThriftTest
-
 namespace * thrift.test
 
 /**
@@ -374,4 +368,4 @@
 struct StructB {
   1: optional StructA aa;
   2: required StructA ab;
-}
+}
\ No newline at end of file