Compile with NDK r12, using clang compiler.

Enable it with adding "-DANDROID_TOOLCHAIN_NAME=clang".

android.toolchain.cmake

@@ -239,7 +239,7 @@ set( ANDROID_SUPPORTED_ABIS_mips "mips" )
 set( ANDROID_SUPPORTED_ABIS_mips64 "mips64" )
 
 # API level defaults
-set( ANDROID_DEFAULT_NDK_API_LEVEL 8 )
+set( ANDROID_DEFAULT_NDK_API_LEVEL 14 )
 set( ANDROID_DEFAULT_NDK_API_LEVEL_arm64 21 )
 set( ANDROID_DEFAULT_NDK_API_LEVEL_x86 9 )
 set( ANDROID_DEFAULT_NDK_API_LEVEL_x86_64 21 )
@@ -730,7 +730,7 @@ else()
 endif()
 
 # choose toolchain
-if( ANDROID_TOOLCHAIN_NAME )
+if( ANDROID_TOOLCHAIN_NAME AND NOT ${ANDROID_TOOLCHAIN_NAME} STREQUAL "clang")
  list( FIND __availableToolchains "${ANDROID_TOOLCHAIN_NAME}" __toolchainIdx )
  if( __toolchainIdx EQUAL -1 )
   list( SORT __availableToolchains )
@@ -768,6 +768,7 @@ unset( __toolchainArch )
 if( __toolchainIdx EQUAL -1 )
  message( FATAL_ERROR "No one of available compiler toolchains is able to compile for ${ANDROID_ARCH_NAME} platform." )
 endif()
+set( ANDROID_TOOLCHAIN_NAME_ARG ${ANDROID_TOOLCHAIN_NAME})
 list( GET __availableToolchains ${__toolchainIdx} ANDROID_TOOLCHAIN_NAME )
 list( GET __availableToolchainMachines ${__toolchainIdx} ANDROID_TOOLCHAIN_MACHINE_NAME )
 list( GET __availableToolchainCompilerVersions ${__toolchainIdx} ANDROID_COMPILER_VERSION )
@@ -959,6 +960,13 @@ elseif( "${ANDROID_TOOLCHAIN_NAME}" MATCHES "-clang3[.][0-9]?$" )
  endif()
  set( ANDROID_COMPILER_IS_CLANG 1 )
  set( ANDROID_CLANG_TOOLCHAIN_ROOT "${ANDROID_NDK_TOOLCHAINS_PATH}/llvm-${ANDROID_CLANG_VERSION}${ANDROID_NDK_TOOLCHAINS_SUBPATH}" )
+elseif( "${ANDROID_TOOLCHAIN_NAME_ARG}" STREQUAL "clang" )
+ if( NOT EXISTS "${ANDROID_NDK_TOOLCHAINS_PATH}/llvm${ANDROID_NDK_TOOLCHAINS_SUBPATH}/bin/clang${TOOL_OS_SUFFIX}" )
+  message( FATAL_ERROR "Could not find the Clang compiler driver" )
+ endif()
+ set( ANDROID_GCC_TOOLCHAIN_NAME "${ANDROID_TOOLCHAIN_NAME}" )
+ set( ANDROID_COMPILER_IS_CLANG 1 )
+ set( ANDROID_CLANG_TOOLCHAIN_ROOT "${ANDROID_NDK_TOOLCHAINS_PATH}/llvm${ANDROID_NDK_TOOLCHAINS_SUBPATH}" )
 else()
  set( ANDROID_GCC_TOOLCHAIN_NAME "${ANDROID_TOOLCHAIN_NAME}" )
  unset( ANDROID_COMPILER_IS_CLANG CACHE )
@@ -1363,6 +1371,8 @@ if( ANDROID_COMPILER_VERSION VERSION_EQUAL "4.6" )
  endif()
 endif() # version 4.6
 
+set( ANDROID_ASM_FLAGS "${ANDROID_CXX_FLAGS}" )
+
 if( ANDROID_NOEXECSTACK )
  if( ANDROID_COMPILER_IS_CLANG )
   set( ANDROID_CXX_FLAGS    "${ANDROID_CXX_FLAGS} -Xclang -mnoexecstack" )
@@ -1377,14 +1387,15 @@ if( ANDROID_RELRO )
 endif()
 
 if( ANDROID_COMPILER_IS_CLANG )
+ set( CXX_FLAGS "-std=c++14" )
  set( ANDROID_CXX_FLAGS "-target ${ANDROID_LLVM_TRIPLE} -Qunused-arguments ${ANDROID_CXX_FLAGS}" )
  if( BUILD_WITH_ANDROID_NDK )
   set( ANDROID_CXX_FLAGS "-gcc-toolchain ${ANDROID_TOOLCHAIN_ROOT} ${ANDROID_CXX_FLAGS}" )
  endif()
 endif()
 
 # cache flags
-set( CMAKE_CXX_FLAGS           ""                        CACHE STRING "c++ flags" )
+set( CMAKE_CXX_FLAGS           "${CXX_FLAGS}"            CACHE STRING "c++ flags" )
 set( CMAKE_C_FLAGS             ""                        CACHE STRING "c flags" )
 set( CMAKE_CXX_FLAGS_RELEASE   "-O3 -DNDEBUG"            CACHE STRING "c++ Release flags" )
 set( CMAKE_C_FLAGS_RELEASE     "-O3 -DNDEBUG"            CACHE STRING "c Release flags" )
@@ -1403,6 +1414,7 @@ set( ANDROID_LINKER_FLAGS      "${ANDROID_LINKER_FLAGS}"      CACHE INTERNAL "An
 # finish flags
 set( CMAKE_CXX_FLAGS           "${ANDROID_CXX_FLAGS} ${CMAKE_CXX_FLAGS}" )
 set( CMAKE_C_FLAGS             "${ANDROID_CXX_FLAGS} ${CMAKE_C_FLAGS}" )
+set( CMAKE_ASM_FLAGS           "${ANDROID_ASM_FLAGS} ${CMAKE_CXX_FLAGS_RELEASE}" )
 set( CMAKE_CXX_FLAGS_RELEASE   "${ANDROID_CXX_FLAGS_RELEASE} ${CMAKE_CXX_FLAGS_RELEASE}" )
 set( CMAKE_C_FLAGS_RELEASE     "${ANDROID_CXX_FLAGS_RELEASE} ${CMAKE_C_FLAGS_RELEASE}" )
 set( CMAKE_CXX_FLAGS_DEBUG     "${ANDROID_CXX_FLAGS_DEBUG} ${CMAKE_CXX_FLAGS_DEBUG}" )
@@ -1526,7 +1538,7 @@ set( BUILD_ANDROID True )
 set( CMAKE_FIND_ROOT_PATH "${ANDROID_TOOLCHAIN_ROOT}/bin" "${ANDROID_TOOLCHAIN_ROOT}/${ANDROID_TOOLCHAIN_MACHINE_NAME}" "${ANDROID_SYSROOT}" "${CMAKE_INSTALL_PREFIX}" "${CMAKE_INSTALL_PREFIX}/share" )
 
 # only search for libraries and includes in the ndk toolchain
-set( CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY )
+set( CMAKE_FIND_ROOT_PATH_MODE_PROGRAM BOTH )
 set( CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY )
 set( CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY )