No more flexible array members (not standard C++) (#1307)

* Replace FAMs with `std::vector`s (or one `std::string`) in four `struct`s

* Anonymous types declared in an anonymous union are also non-standard
  Only Clang complains about this (-Wnested-anon-types)

include/asm/fstack.hpp

@@ -9,6 +9,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string>
+#include <vector>
 
 #include "asm/lexer.hpp"
 
@@ -28,14 +29,12 @@ struct FileStackNode {
 
 struct FileStackReptNode { // NODE_REPT
 	struct FileStackNode node;
-	uint32_t reptDepth;
-	// WARNING: if changing this type, change overflow check in `fstk_Init`
-	uint32_t iters[]; // REPT iteration counts since last named node, in reverse depth order
+	std::vector<uint32_t> *iters; // REPT iteration counts since last named node, in reverse depth order
 };
 
 struct FileStackNamedNode { // NODE_FILE, NODE_MACRO
 	struct FileStackNode node;
-	char name[]; // File name for files, file::macro name for macros
+	std::string *name; // File name for files, file::macro name for macros
 };
 
 #define DEFAULT_MAX_DEPTH 64