compat: drop uncompress2() compatibility shim

Our compat library has an implementation of zlib's `uncompress2()`
function that gets used when linking against an old version of zlib
that doesn't yet have it. The last user of `uncompress2()` got removed
in 15a60b7 (reftable/block: open-code call to `uncompress2()`,
2024-04-08), so the compatibility code is not required anymore. Drop it.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

Makefile

@@ -984,7 +984,6 @@ LIB_OBJS += commit.o
 LIB_OBJS += compat/nonblock.o
 LIB_OBJS += compat/obstack.o
 LIB_OBJS += compat/terminal.o
-LIB_OBJS += compat/zlib-uncompress2.o
 LIB_OBJS += config.o
 LIB_OBJS += connect.o
 LIB_OBJS += connected.o

compat/zlib-uncompress2.c

@@ -1540,15 +1540,6 @@ int common_exit(const char *file, int line, int code);
 #define z_const
 #include <zlib.h>
 
-#if ZLIB_VERNUM < 0x1290
-/*
- * This is uncompress2, which is only available in zlib >= 1.2.9
- * (released as of early 2017). See compat/zlib-uncompress2.c.
- */
-int uncompress2(Bytef *dest, uLongf *destLen, const Bytef *source,
-		uLong *sourceLen);
-#endif
-
 /*
  * This include must come after system headers, since it introduces macros that
  * replace system names.

git-compat-util.h

@@ -263,7 +263,6 @@ libgit_sources = [
   'compat/nonblock.c',
   'compat/obstack.c',
   'compat/terminal.c',
-  'compat/zlib-uncompress2.c',
   'config.c',
   'connect.c',
   'connected.c',