merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/banned.h

@@ -0,0 +1,32 @@
+#ifndef BANNED_H
+#define BANNED_H
+
+/*
+ * This header lists functions that have been banned from our code base,
+ * because they're too easy to misuse (and even if used correctly,
+ * complicate audits). Including this header turns them into compile-time
+ * errors.
+ */
+
+#define BANNED(func) sorry_##func##_is_a_banned_function
+
+#undef strcpy
+#define strcpy(x,y) BANNED(strcpy)
+#undef strcat
+#define strcat(x,y) BANNED(strcat)
+#undef strncpy
+#define strncpy(x,y,n) BANNED(strncpy)
+#undef strncat
+#define strncat(x,y,n) BANNED(strncat)
+
+#undef sprintf
+#undef vsprintf
+#ifdef HAVE_VARIADIC_MACROS
+#define sprintf(...) BANNED(sprintf)
+#define vsprintf(...) BANNED(vsprintf)
+#else
+#define sprintf(buf,fmt,arg) BANNED(sprintf)
+#define vsprintf(buf,fmt,arg) BANNED(sprintf)
+#endif
+
+#endif /* BANNED_H */