Make failedOnMissingInclude not extern

src/asm/fstack.cpp

@@ -46,6 +46,7 @@ static std::stack<Context> contextStack;
 // The first include path for `fstk_FindFile` to try is none at all
 static std::vector<std::string> includePaths = {""}; // -I
 static std::deque<std::string> preIncludeNames;      // -P
+static bool failedOnMissingInclude = false;
 
 std::string FileStackNode::reptChain() const {
 	std::string chain;
@@ -317,6 +318,10 @@ bool fstk_FileError(std::string const &path, char const *functionName) {
 	return false;
 }
 
+bool fstk_FailedOnMissingInclude() {
+	return failedOnMissingInclude;
+}
+
 bool fstk_RunInclude(std::string const &path) {
 	if (std::optional<std::string> fullPath = fstk_FindFile(path); fullPath) {
 		newFileContext(*fullPath, false);