Added aws_error* functions to native extension (#12)

* Added aws_crt_error_str and test, removed awscrt_version test function

* Added aws_crt_error_name

* Added aws_crt_error_debug_str

* Use PHP's own tools to generate arginfo

* Only re-generate arginfo on php7+

* Added a definition for ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX for php5

* Ignore generated files for clang-format

format-check.sh

@@ -10,7 +10,7 @@ if NOT type $CLANG_FORMAT 2> /dev/null ; then
 fi
 
 FAIL=0
-SOURCE_FILES=`find ext -type f \( -name '*.h' -o -name '*.c' \)`
+SOURCE_FILES=`find src ext -type f \( -name '*.h' -o -name '*.c' \)`
 for i in $SOURCE_FILES
 do
     $CLANG_FORMAT -output-replacements-xml $i | grep -c "<replacement " > /dev/null