qt-base: fix build on macos, when +network (#38519)

* qt-base: always link to GSS framework on macOS

On macos, the code in src/network/kernel/qauthenticator.cpp
unconditionally includes the header from the GSS framework, so we should
link against it.

This applies two patches from the dev branch. They are to be cherry-picked
into the 6.5 (probably released with 6.5.2) and 6.6 branches, but they
apply against 6.3.2 as well.

* qt-base: disable libproxy on macOS

src/network/CMakeLists.txt disables it on MACOS anyway. And as it is not
found without pkg-config, building with +network would break because of
the feature being explicitly enabled.

* qt-base: don't depend on pkgconfig on macOS

On macOS, usage of pkg-config is disabled by unsetting
PKG_CONFIG_EXECUTABLE, unless the feature pkg-config is requested explicitly.

* qt-base: don't depend on at-spi2-core on macOS

Does not build on macOS and seems to be targeted at linux. Qt6 on
homebrew does not depend on it, either.

* qt-base: fix long lines

* qt-base: restrict use of pkgconfig to linux

yes, probably not needed on windows, either

Co-authored-by: Alec Scott <alec@bcs.sh>

* qt-base: disable libproxy on Windows as well

according to src/network/CMakeLists.txt it's only used on Unix

* qt-base: improvements based on reviewer suggestions

---------

Co-authored-by: Alec Scott <alec@bcs.sh>

var/spack/repos/builtin/packages/qt-base/package.py

@@ -36,7 +36,7 @@ def get_list_url(qualname):
     # Default dependencies for all qt-* components
     generator("ninja")
     depends_on("cmake@3.16:", type="build")
-    depends_on("pkgconfig", type="build")
+    depends_on("pkgconfig", type="build", when="platform=linux")
     depends_on("python", type="build")
 
     # List of unnecessary directories in src/3rdparty
@@ -130,8 +130,7 @@ class QtBase(QtPackage):
     depends_on("zstd")
     with when("platform=linux"):
         depends_on("libdrm")
-
-    depends_on("at-spi2-core", when="+accessibility")
+        depends_on("at-spi2-core", when="+accessibility")
     depends_on("dbus", when="+dbus")
     depends_on("gl", when="+opengl")
     depends_on("sqlite", when="+sql")
@@ -148,12 +147,24 @@ class QtBase(QtPackage):
             depends_on("libxrender")
 
     with when("+network"):
-        depends_on("libproxy")
         depends_on("openssl")
+        with when("platform=linux"):
+            depends_on("libproxy")
 
     # Qt6 requires newer compilers: see https://github.com/spack/spack/issues/34418
     conflicts("%gcc@:7")
 
+    # ensure that Qt links against GSS framework on macOS: https://bugreports.qt.io/browse/QTBUG-114537
+    with when("@6.3.2:6.5.1"):
+        patch(
+            "https://github.com/qt/qtbase/commit/c3d3e7312499189dde2ff9c0cb14bd608d6fd1cd.patch?full_index=1",
+            sha256="85c16db15406b0094831bb57016dab7e0c0fd0978b082a1dc103c87334db7915",
+        )
+        patch(
+            "https://github.com/qt/qtbase/commit/1bf144ba78ff10d712b4de55d2797b9256948a1d.patch?full_index=1",
+            sha256="e4d9f1aee0566558e77eef5609b63c1fde3f3986bea1b9d5d7930b297f916a5e",
+        )
+
     @property
     def archive_files(self):
         """Save both the CMakeCache and the config summary."""
@@ -211,7 +222,9 @@ def define_feature(key, variant=None):
         if "+dbus" in spec:
             features.append("dbus_linked")
         if "+network" in spec:
-            features += ["openssl_linked", "openssl", "libproxy"]
+            features.extend(["openssl_linked", "openssl"])
+            if sys.platform == "linux":
+                features.append("libproxy")
         for k in features:
             define("FEATURE_" + k, True)