Don't bail out if got include unrelated error while preprocessing

Preprocessing is a bit tricky, since it expects an error to resolve missing includes; to do this, it invokes gcc with -CC flag (https://gcc.gnu.org/onlinedocs/gcc-4.4.0/gcc/Preprocessor-Options.html#Preprocessor-Options) to expand macro AND comments. Since this flag is not used during normal compilation, the errors reported are mostly bogus.

This patch avoids writing the actual (non-include) error on stdout so the compilation can go on and fail on the proper errors (if there's any)

container_find_includes.go

@@ -343,11 +343,6 @@ func findIncludesUntilDone(ctx *types.Context, cache *includeCache, sourceFile t
 				return i18n.WrapError(preproc_err)
 			} else {
 				include = IncludesFinderWithRegExp(ctx, string(preproc_stderr))
-				if include == "" {
-					// No include found? Bail out.
-					os.Stderr.Write(preproc_stderr)
-					return i18n.WrapError(preproc_err)
-				}
 			}
 		}