Merge pull request #1730 from bggd/patch-3

Add error for C99 style variable declaration on travis-ci

tasks/toolchains/gcc.rake

 MRuby::Toolchain.new(:gcc) do |conf|
   [conf.cc, conf.objc, conf.asm].each do |cc|
     cc.command = ENV['CC'] || 'gcc'
-    cc.flags = [ENV['CFLAGS'] || %w(-g -std=gnu99 -O3 -Wall -Werror-implicit-function-declaration -Wdeclaration-after-statement -Werror=declaration-after-statement)]
+    cc.flags = [ENV['CFLAGS'] || %w(-g -std=gnu99 -O3 -Wall -Werror-implicit-function-declaration -Wdeclaration-after-statement)]
     cc.include_paths = ["#{MRUBY_ROOT}/include"]
     cc.defines = %w(DISABLE_GEMS)
     cc.option_include_path = '-I%s'

travis_config.rb

@@ -4,6 +4,7 @@ MRuby::Build.new('debug') do |conf|
 
   # include all core GEMs
   conf.gembox 'full-core'
+  conf.cc.flags += %w(-Werror=declaration-after-statement)
   conf.cc.defines += %w(MRB_GC_FIXED_ARENA)
 end
 
@@ -12,6 +13,7 @@ MRuby::Build.new do |conf|
 
   # include all core GEMs
   conf.gembox 'full-core'
+  conf.cc.flags += %w(-Werror=declaration-after-statement)
   conf.cc.defines = %w(MRB_DEBUG MRB_GC_FIXED_ARENA)
   conf.enable_bintest = true
 end