Give these two structs a tag name. C++20 forbids default member
initializers in an unnamed class that is given a typedef name for linkage
purposes, which MSVC reports as the hard error C7626. Naming the class
takes it out of that rule. clang and gcc accept it either way.

--- afdko/c/addfeatures/hotconv/sfnt.cpp
+++ afdko/c/addfeatures/hotconv/sfnt.cpp
@@ -77,7 +77,7 @@
 
 /* ---------------------------- Table Definition --------------------------- */
 
-typedef struct {
+typedef struct Entry {
     int32_t tag = 0;
     uint32_t checksum = 0;
     uint32_t offset = 0;
@@ -85,7 +85,7 @@
 } Entry;
 #define ENTRY_SIZE (uint32 * 4)
 
-typedef struct {
+typedef struct sfntTbl {
     Fixed version = 0;
     uint16_t numTables = 0;
     uint16_t searchRange = 0;