Rely only on pkg-config to find zlib include directory

[sagudev]

This solves servo/servo#31851 for me. The problem is that if libz is installed on system we add it's path to includes which causes problems. I think we do not need this as SM build system depends on pkg-config to find this.

[sagudev]

Relevant configure code:

mozjs/mozjs-sys/mozjs/moz.configure

Lines 895 to 936 in b695c63

	@depends(js_standalone, target)
	def system_zlib_default(js_standalone, target):
	return (
	js_standalone
	and target.kernel not in ("WINNT", "Darwin")
	and target.os != "Android"
	)
	option(
	"--with-system-zlib",
	nargs="?",
	default=system_zlib_default,
	help="{Use|Do not use} system libz",
	)
	@depends("--with-system-zlib")
	def deprecated_system_zlib_path(value):
	if len(value) == 1:
	die(
	"--with-system-zlib=PATH is not supported anymore. Please use "
	"--with-system-zlib and set any necessary pkg-config environment variable."
	)
	pkg_check_modules("MOZ_ZLIB", "zlib >= 1.2.3", when="--with-system-zlib")
	set_config("MOZ_SYSTEM_ZLIB", True, when="--with-system-zlib")
	@depends("--with-system-zlib", js_shared, moz_linker, target.os)
	def zlib_in_mozglue(system_zlib, js_shared, linker, os):
	if not system_zlib and (js_shared or linker or os == "Android"):
	return True
	set_config("ZLIB_IN_MOZGLUE", zlib_in_mozglue)
	set_define("ZLIB_IN_MOZGLUE", zlib_in_mozglue)

[sagudev]

System zlib is only used on linux, on other platform (android, darwin, windows) it is built from sources, and the only way to detect it on system is via pkg-config (which windows env does not have even in moztools).

[sagudev]

We could potentially completely remove libz dependency and instead relay on included zlib on linux too, or just limit libz on linux target.