LibC: Add __fseterr

This is used by some ports to not require internal FILE structure

userspace/libraries/LibC/include/stdio.h

@@ -127,6 +127,8 @@ int		vsnprintf(char* __restrict s, size_t n, const char* __restrict format, va_l
 int		vsprintf(char* __restrict s, const char* __restrict format, va_list ap);
 int		vsscanf(const char* __restrict s, const char* __restrict format, va_list arg);
 
+void __fseterr(FILE* stream);
+
 __END_DECLS
 
 #endif

userspace/libraries/LibC/stdio.cpp

@@ -134,6 +134,12 @@ void clearerr(FILE* file)
 	file->error = false;
 }
 
+void __fseterr(FILE* file)
+{
+	ScopeLock _(file);
+	file->error = true;
+}
+
 char* ctermid(char* buffer)
 {
 	static char s_buffer[L_ctermid];