Merge pull request #2896 from sagmor/custom-gcc-version

Add ability to change compiler versions for androideabi

tasks/toolchains/androideabi.rake

@@ -27,6 +27,8 @@ MRuby::Toolchain.new(:androideabi) do |conf|
   ANDROID_TARGET_ARCH = ENV['ANDROID_TARGET_ARCH'] || DEFAULT_ANDROID_TARGET_ARCH
   ANDROID_TARGET_ARCH_ABI = ENV['ANDROID_TARGET_ARCH_ABI'] || DEFAULT_ANDROID_TARGET_ARCH_ABI
   ANDROID_TOOLCHAIN = ENV['ANDROID_TOOLCHAIN'] || DEFAULT_ANDROID_TOOLCHAIN
+  GCC_VERSION = ENV['GCC_VERSION'] || GCC_VERSION
+  CLANG_VERSION = ENV['CLANG_VERSION'] || CLANG_VERSION
 
   case ANDROID_TARGET_ARCH.downcase
   when 'arch-arm',  'arm'  then
@@ -74,9 +76,9 @@ MRuby::Toolchain.new(:androideabi) do |conf|
       else
         # Any other architecture are not supported by Android NDK.
       end
-      path_to_toolchain += DEFAULT_GCC_VERSION + '/prebuilt/' + HOST_PLATFORM
+      path_to_toolchain += GCC_VERSION + '/prebuilt/' + HOST_PLATFORM
     else
-      path_to_toolchain += 'llvm-' + DEFAULT_CLANG_VERSION + '/prebuilt/' + HOST_PLATFORM
+      path_to_toolchain += 'llvm-' + CLANG_VERSION + '/prebuilt/' + HOST_PLATFORM
     end
   else
     path_to_toolchain = ANDROID_STANDALONE_TOOLCHAIN