Fix compilation warnings in Lua and jemalloc dependencies (#7785)

- The argument `u` in for `ar` is ignored (and generates warnings since `D` became the default.
  All it does is avoid updating unchanged objects (shouldn't have any impact on our build)
- Enable `LUA_USE_MKSTEMP` to force the use of `mkstemp()` instead of `tmpname()` (which is dead
  code in redis anyway).
- Remove unused variable `c` in `f_parser()`
- Removed misleadingly indented space in `luaL_loadfile()` and ``addfield()`

Co-authored-by: Oran Agra <oran@redislabs.com>

deps/jemalloc/configure.ac

@@ -517,7 +517,7 @@ CTARGET='-o $@'
 LDTARGET='-o $@'
 TEST_LD_MODE=
 EXTRA_LDFLAGS=
-ARFLAGS='crus'
+ARFLAGS='crs'
 AROUT=' $@'
 CC_MM=1