cmake: update to work with CMake 3.2.2

Summary:
Update the CMake build scripts to work with CMake 3.2.2, as well as older boost
libraries.

Several other open source Facebook projects have CI that checks that the code
builds with modified Ubuntu 14.04 systems (Ubuntu 14.04 + gcc 4.9 +
CMake 3.2.2).  By default Ubuntu 14.04 ships with gcc 4.8.2 and CMake 2.8; we
do not support vanilla Ubuntu 14.04.

Reviewed By: yfeldblum

Differential Revision: D6806326

fbshipit-source-id: 243f2f9cea20c7a9430dc386c921e3cafeee77f7

CMake/FollyConfigChecks.cmake

 include(CheckCXXSourceCompiles)
 include(CheckCXXSourceRuns)
 include(CheckFunctionExists)
-include(CheckIncludeFile)
+include(CheckIncludeFileCXX)
 include(CheckSymbolExists)
 include(CheckTypeSize)
 include(CheckCXXCompilerFlag)

CMake/folly-deps.cmake

 include(CheckCXXSourceCompiles)
+include(CheckIncludeFileCXX)
 
-find_package(Boost 1.55.0 MODULE
+find_package(Boost 1.51.0 MODULE
   COMPONENTS
     context
     chrono
@@ -12,17 +13,8 @@ find_package(Boost 1.55.0 MODULE
     thread
   REQUIRED
 )
-set(FOLLY_SHINY_DEPENDENCIES
-  Boost::chrono
-  Boost::context
-  Boost::date_time
-  Boost::filesystem
-  Boost::program_options
-  Boost::regex
-  Boost::system
-  OpenSSL::SSL
-  OpenSSL::Crypto
-)
+list(APPEND FOLLY_LINK_LIBRARIES ${Boost_LIBRARIES})
+list(APPEND FOLLY_INCLUDE_DIRECTORIES ${Boost_INCLUDE_DIRS})
 
 find_package(DoubleConversion MODULE REQUIRED)
 list(APPEND FOLLY_LINK_LIBRARIES ${DOUBLE_CONVERSION_LIBRARY})
@@ -69,6 +61,8 @@ else()
 endif()
 
 find_package(OpenSSL MODULE REQUIRED)
+list(APPEND FOLLY_LINK_LIBRARIES ${OPENSSL_LIBRARIES})
+list(APPEND FOLLY_INCLUDE_DIRECTORIES ${OPENSSL_INCLUDE_DIR})
 
 find_package(PThread MODULE)
 set(FOLLY_HAVE_PTHREAD ${LIBPTHREAD_FOUND})

CMakeLists.txt

-cmake_minimum_required(VERSION 3.4.0 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.2.0 FATAL_ERROR)
 
 # includes
 set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/CMake" ${CMAKE_MODULE_PATH})
@@ -14,7 +14,7 @@ set(PACKAGE_BUGREPORT "https://github.com/facebook/folly/issues")
 # 150+ tests in the root folder anyone? No? I didn't think so.
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 
-project(${PACKAGE_NAME} CXX)
+project(${PACKAGE_NAME} CXX C)
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
   # Check target architecture
@@ -363,7 +363,7 @@ if (BUILD_TESTS)
   )
   target_link_libraries(folly_test_support
     PUBLIC
-      Boost::thread
+      ${BOOST_LIBRARIES}
       follybenchmark
       folly
       ${LIBGMOCK_LIBRARIES}