CMake improvements

Summary:
- Allow setting custom installation prefix.
- Add option to disable building tests.
Closes https://github.com/facebook/rocksdb/pull/2195

Differential Revision: D5054239

Pulled By: sagar0

fbshipit-source-id: 2de6bef8b7eafed60a830e1796b262f9e6f79da0

CMakeLists.txt

@@ -635,6 +635,26 @@ else()
   message(STATUS "JNI library is disabled")
 endif()
 
+# Installation and packaging
+if(WIN32)
+  option(ROCKSDB_INSTALL_ON_WINDOWS "Enable install target on Windows" OFF)
+endif()
+if(NOT WIN32 OR ROCKSDB_INSTALL_ON_WINDOWS)
+  if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
+    if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
+      # Change default installation prefix on Linux to /usr
+      set(CMAKE_INSTALL_PREFIX /usr CACHE PATH "Install path prefix, prepended onto install directories." FORCE)
+    endif()
+  endif()
+
+  include(GNUInstallDirs)
+  install(TARGETS ${ROCKSDB_STATIC_LIB} COMPONENT devel ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
+  install(TARGETS ${ROCKSDB_SHARED_LIB} COMPONENT runtime DESTINATION ${CMAKE_INSTALL_LIBDIR})
+  install(DIRECTORY include/rocksdb COMPONENT devel DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+endif()
+
+option(WITH_TESTS "build with tests" ON)
+if(WITH_TESTS)
 set(TESTS
         cache/cache_test.cc
         cache/lru_cache_test.cc
@@ -846,14 +866,9 @@ foreach(sourcefile ${C_TEST_EXES})
     add_test(NAME ${exename} COMMAND ${exename}${ARTIFACT_SUFFIX})
     add_dependencies(check ${exename}${ARTIFACT_SUFFIX})
 endforeach(sourcefile ${C_TEST_EXES})
-add_subdirectory(tools)
-
-# Installation and packaging for Linux
-if(NOT WIN32)
-install(TARGETS ${ROCKSDB_STATIC_LIB} COMPONENT devel ARCHIVE DESTINATION lib64)
-install(TARGETS ${ROCKSDB_SHARED_LIB} COMPONENT runtime DESTINATION lib64)
-install(DIRECTORY "${PROJECT_SOURCE_DIR}/include/rocksdb/"
-        COMPONENT devel
-        DESTINATION include/rocksdb)
-set(CMAKE_INSTALL_PREFIX /usr)
+endif()
+
+option(WITH_TOOLS "build with tools" ON)
+if(WITH_TOOLS)
+  add_subdirectory(tools)
 endif()