rgbasm: Report conflicting file/line number for duplicate sections

include/asm/section.h

@@ -22,6 +22,8 @@ struct Section {
 	char *name;
 	enum SectionType type;
 	enum SectionModifier modifier;
+	struct FileStackNode *src; /* Where the section was defined */
+	uint32_t fileLine; /* Line where the section was defined */
 	uint32_t size;
 	uint32_t org;
 	uint32_t bank;