Typo.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@279491 91177308-0d34-0410-b5e6-96231b3b80d8

test/Modules/ExtDebugInfo.cpp

 // RUN: rm -rf %t
-// Test that only forward declarations are emitted for types dfined in modules.
+// Test that only forward declarations are emitted for types defined in modules.
 
 // Modules:
 // RUN: %clang_cc1 -x objective-c++ -std=c++11 -debug-info-kind=standalone \