Tests/RunCMake/CMP0156: Match expected results more precisely

Tests/RunCMake/CMP0156/CMP0156-OLD-AppleClang-build-result.txt

@@ -1 +1 @@
-.+
+[^0]

Tests/RunCMake/CMP0156/CMP0156-OLD-AppleClang-build-stdout.txt

@@ -1,3 +1,3 @@
-ld: warning: ignoring duplicate libraries: '.*liblib1.a', '.*liblib2.a'
+ld: warning: ignoring duplicate libraries: '[^']*liblib1\.a', '[^']*liblib2\.a'
 ld: fatal warning\(s\) induced error \(-fatal_warnings\)
 (cc|clang): error: linker command failed with exit code 1 \(use -v to see invocation\)