Keep -iframework if present in parsed C/C++ flags (#3057)

* Keep -iframework if present in parsed C/C++ flags
* Add test to make sure -iframework is parsed

Co-authored-by: Alex Wang <ts826848@gmail.com>

autoload/ale/c.vim

@@ -132,6 +132,7 @@ function! ale#c#ParseCFlags(path_prefix, cflag_line) abort
         \ || stridx(l:option, '-iquote') == 0
         \ || stridx(l:option, '-isystem') == 0
         \ || stridx(l:option, '-idirafter') == 0
+        \ || stridx(l:option, '-iframework') == 0
             if stridx(l:option, '-I') == 0 && l:option isnot# '-I'
                 let l:arg = join(split(l:option, '\zs')[2:], '')
                 let l:option = '-I'