[cmake/win32] Don't use system wide installed dependencies

Empty PATH (except VS Toolchain/bin) so that CMake won't pick up system
wide installed dependencies (such as MySql or Python).

cmake/scripts/windows/ArchSetup.cmake

@@ -18,6 +18,12 @@ list(APPEND CMAKE_SYSTEM_PREFIX_PATH ${CMAKE_SOURCE_DIR}/project/BuildDependenci
 
 set(PYTHON_INCLUDE_DIR ${CMAKE_SOURCE_DIR}/project/BuildDependencies/include/python)
 
+# The find_* functions prefer PATH over CMAKE_PREFIX_PATH for dependencies.
+# Emptying PATH so that system installed libraries (MySql, Python) are not picked up.
+# The VS/bin directory has to be in PATH for example for NMake.
+get_filename_component(TOOLCHAIN_PATH ${CMAKE_CXX_COMPILER} DIRECTORY)
+set(ENV{PATH} "${TOOLCHAIN_PATH}")
+
 
 # -------- Compiler options ---------