Merge topic 'test-FindPkgConfig-isolate-env' into release-3.18

8b12982653 Merge branch 'backport-test-FindPkgConfig-isolate-env'
4c939b0d39 Tests: Isolate RunCMake.FindPkgConfig from caller environment
20eeb40aaf Tests: Isolate RunCMake.FindPkgConfig from caller environment

Acked-by: Kitware Robot <[email protected]>
Merge-request: !5108

Tests/RunCMake/FindPkgConfig/RunCMakeTest.cmake

@@ -1,5 +1,10 @@
 include(RunCMake)
 
+# Isolate test cases from caller's environment.
+set(ENV{CMAKE_PREFIX_PATH} "")
+set(ENV{CMAKE_APPBUNDLE_PATH} "")
+set(ENV{CMAKE_FRAMEWORK_PATH} "")
+
 run_cmake(PkgConfigDoesNotExist)
 
 run_cmake(FindPkgConfig_NO_PKGCONFIG_PATH)