Refactor how CCache is set up

* Use RULE_LAUNCH_COMPILE property as you're apparently supposed to
* Detect if compiler is already ccache to prevent build failure

CMakeLists.txt

@@ -26,6 +26,8 @@ include(CheckLibraryExists)
 include(CMakeDependentOption)
 include(CheckIPOSupported)
 
+include(SetupCCache)
+
 set(CMAKE_OSX_DEPLOYMENT_TARGET "10.15" CACHE STRING "Minimum OS X deployment version")
 
 set(CMAKE_C_STANDARD 11)
@@ -91,13 +93,6 @@ endif()
 
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
-find_program(CCACHE "ccache")
-if (CCACHE)
-    message(STATUS "Using CCache to speed up compilation")
-    set(CMAKE_C_COMPILER_LAUNCHER ${CCACHE})
-    set(CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE})
-endif()
-
 option(ENABLE_GDBSTUB "Enable GDB stub" ON)
 if (ENABLE_GDBSTUB)
     add_definitions(-DGDBSTUB_ENABLED)

cmake/SetupCCache.cmake

@@ -0,0 +1,19 @@
+include(FindPackageMessage)
+
+find_program(CCACHE "ccache")
+
+cmake_dependent_option(USE_CCACHE "Use CCache to speed up repeated builds." ON CCACHE OFF)
+
+if (NOT CCACHE OR NOT USE_CCACHE)
+    return()
+endif()
+
+# Fedora, and probably also Red Hat-based distros in general, use CCache by default if it's installed on the system.
+# We'll try to detect this here, and exit if that's the case.
+# Trying to launch ccache with ccache as we'd otherwise do seems to cause build issues.
+if (CMAKE_C_COMPILER MATCHES "ccache" OR CMAKE_CXX_COMPILER MATCHES "ccache")
+    return()
+endif()
+
+find_package_message(CCache "Using CCache to speed up compilation" "${USE_CCACHE}")
+set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE}")