Configure ccache in CMakeLists.txt to speed up compilation

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/5388

Differential Revision: D15579052

Pulled By: siying

fbshipit-source-id: ee58770fe023f40b9aa189a225e4c7ef50613ea9

CMakeLists.txt

@@ -44,6 +44,12 @@ endif()
 
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake/modules/")
 
+find_program(CCACHE_FOUND ccache)
+if(CCACHE_FOUND)
+  set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ccache)
+  set_property(GLOBAL PROPERTY RULE_LAUNCH_LINK ccache)
+endif(CCACHE_FOUND)
+
 option(WITH_JEMALLOC "build with JeMalloc" OFF)
 option(WITH_SNAPPY "build with SNAPPY" OFF)
 option(WITH_LZ4 "build with lz4" OFF)