Tests: Avoid interference from environment in RunCMake.find_library

Clear $ENV{CMAKE_PREFIX_PATH} in several RunCMake.find_library tests
because on Windows, a CMAKE_PREFIX_PATH with two consecutive
semicolons causes a library to be found when it should not be.

None of the updated tests expect CMAKE_PREFIX_PATH from the environment
to influence the test, so clear the variable entirely to guarantee it
will not affect the test.

Fixes: #23111
Signed-off-by: William R. Dieter <[email protected]>

Tests/RunCMake/find_library/FromPATHEnv.cmake

@@ -1,6 +1,8 @@
 list(APPEND CMAKE_FIND_LIBRARY_PREFIXES lib)
 list(APPEND CMAKE_FIND_LIBRARY_SUFFIXES .a)
 set(ENV_PATH "$ENV{PATH}")
+set(ENV_CMAKE_PREFIX_PATH "$ENV{CMAKE_PREFIX_PATH}")
+set(ENV{CMAKE_PREFIX_PATH} "")
 file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/lib)
 file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/lib/libcreated.a" "created")
 
@@ -33,3 +35,4 @@ foreach(path "/does_not_exist" "/lib" "")
 endforeach()
 set(CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH ON)
 set(ENV{PATH} "${ENV_PATH}")
+set(ENV{CMAKE_PREFIX_PATH} "${ENV_CMAKE_PREFIX_PATH}")

Tests/RunCMake/find_library/FromPATHEnvDebugVar.cmake

@@ -1,6 +1,8 @@
 list(APPEND CMAKE_FIND_LIBRARY_PREFIXES lib)
 list(APPEND CMAKE_FIND_LIBRARY_SUFFIXES .a)
 set(ENV_PATH "$ENV{PATH}")
+set(ENV_CMAKE_PREFIX_PATH "$ENV{CMAKE_PREFIX_PATH}")
+set(ENV{CMAKE_PREFIX_PATH} "")
 file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/lib)
 file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/lib/libcreated.a" "created")
 
@@ -33,3 +35,4 @@ foreach(path "/does_not_exist" "/lib" "")
 endforeach()
 set(CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH ON)
 set(ENV{PATH} "${ENV_PATH}")
+set(ENV{CMAKE_PREFIX_PATH} "${ENV_CMAKE_PREFIX_PATH}")

Tests/RunCMake/find_library/FromPrefixPath.cmake

@@ -1,7 +1,9 @@
 list(APPEND CMAKE_FIND_LIBRARY_PREFIXES lib)
 list(APPEND CMAKE_FIND_LIBRARY_SUFFIXES .a)
 set(ENV_PATH "$ENV{PATH}")
+set(ENV_CMAKE_PREFIX_PATH "$ENV{CMAKE_PREFIX_PATH}")
 set(ENV{PATH} "")
+set(ENV{CMAKE_PREFIX_PATH} "")
 file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/lib)
 file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/lib/libcreated.a" "created")
 
@@ -22,3 +24,4 @@ foreach(path "/does_not_exist" "/lib" "")
 endforeach()
 set(CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH ON)
 set(ENV{PATH} "${ENV_PATH}")
+set(ENV{CMAKE_PREFIX_PATH} "${ENV_CMAKE_PREFIX_PATH}")