Linux: Relax interdependency between freetype, libpng, and zlib for u…

…nvendored builds

This restriction was added to fix godotengine#7373 back then, which was a symbol conflict
between FreeType's bundled copy of gzip/zlib, and distro packages.

But we also unbundled FreeType's zlib in godotengine#69395 so this is no longer an issue.

modules/freetype/SCsub

@@ -67,7 +67,7 @@ if env["builtin_freetype"]:
     env.Prepend(CPPPATH=[thirdparty_dir + "/include"])
 
     env_freetype.Append(CPPDEFINES=["FT2_BUILD_LIBRARY", "FT_CONFIG_OPTION_USE_PNG", "FT_CONFIG_OPTION_SYSTEM_ZLIB"])
-    if env.dev_build:
+    if env.dev_build and env["builtin_zlib"]:  # Should match what we set in core/SCsub
         env_freetype.Append(CPPDEFINES=["ZLIB_DEBUG"])
 
     # Also requires libpng headers

platform/linuxbsd/detect.py

@@ -216,23 +216,6 @@ def configure(env: "SConsEnvironment"):
 
     # FIXME: Check for existence of the libs before parsing their flags with pkg-config
 
-    # freetype depends on libpng and zlib, so bundling one of them while keeping others
-    # as shared libraries leads to weird issues. And graphite and harfbuzz need freetype.
-    ft_linked_deps = [
-        env["builtin_freetype"],
-        env["builtin_libpng"],
-        env["builtin_zlib"],
-        env["builtin_graphite"],
-        env["builtin_harfbuzz"],
-    ]
-    if (not all(ft_linked_deps)) and any(ft_linked_deps):  # All or nothing.
-        print_error(
-            "These libraries should be either all builtin, or all system provided:\n"
-            "freetype, libpng, zlib, graphite, harfbuzz.\n"
-            "Please specify `builtin_<name>=no` for all of them, or none."
-        )
-        sys.exit(255)
-
     if not env["builtin_freetype"]:
         env.ParseConfig("pkg-config freetype2 --cflags --libs")