Add CMake option to disable ccache

There are situations where ccache causes problems (such as interactions
with other build accelerators) so it's useful to be able to turn it off.
It remains on by default.

CMakeLists.txt

@@ -21,6 +21,7 @@ option(LOCALIZE     "Support for language localizations. Also enable UTF support
 option(LANGUAGES    "Compile localization files for specified languages."   "")
 option(DYNAMIC_LINKING "Use dynamic linking. Or use static to remove MinGW dependency instead."   "ON")
 option(JSON_FORMAT  "Build JSON formatter" "OFF")
+option(CATA_CCACHE  "Try to find and build with ccache" "ON")
 option(CATA_CLANG_TIDY_PLUGIN "Build Cata's custom clang-tidy plugin" "OFF")
 set(CATA_CLANG_TIDY_INCLUDE_DIR "" CACHE STRING "Path to internal clang-tidy headers required for plugin (e.g. ClangTidy.h)")
 set(CATA_CHECK_CLANG_TIDY "" CACHE STRING "Path to check_clang_tidy.py for plugin tests")
@@ -392,9 +393,9 @@ ADD_CUSTOM_TARGET(uninstall
 )
 
 find_program(CCACHE_FOUND ccache)
-if(CCACHE_FOUND)
+if(CCACHE_FOUND AND CATA_CCACHE)
     set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ccache)
     set_property(GLOBAL PROPERTY RULE_LAUNCH_LINK ccache)
-endif(CCACHE_FOUND)
+endif()
 
 # vim:noet