Fix #677 - Ignore errors from other files for cppcheck

autoload/ale/handlers/cppcheck.vim

@@ -4,16 +4,17 @@ function! ale#handlers#cppcheck#HandleCppCheckFormat(buffer, lines) abort
     " Look for lines like the following.
     "
     " [test.cpp:5]: (error) Array 'a[10]' accessed at index 10, which is out of bounds
-    let l:pattern = '^\[.\{-}:\(\d\+\)\]: (\(.\{-}\)) \(.\+\)'
+    let l:pattern = '\v^\[(.+):(\d+)\]: \(([a-z]+)\) (.+)$'
     let l:output = []
 
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
-        call add(l:output, {
-        \   'lnum': l:match[1] + 0,
-        \   'col': 0,
-        \   'text': l:match[3] . ' (' . l:match[2] . ')',
-        \   'type': l:match[2] ==# 'error' ? 'E' : 'W',
-        \})
+        if ale#path#IsBufferPath(a:buffer, l:match[1])
+            call add(l:output, {
+            \   'lnum': str2nr(l:match[2]),
+            \   'type': l:match[3] ==# 'error' ? 'E' : 'W',
+            \   'text': l:match[4],
+            \})
+        endif
     endfor
 
     return l:output