py-pyside2: fix to build with newer llvm and to use spack install headers (#40544)

* Fix py-pyside2 to build with newer llvm and to use spack libglx and libxcb headers where system headers are missing

pyside2 needs LLVM_INSTALL_DIR to be set when using llvm 11: and expects system headers for libglx and libxcb and won't build otherwise.

* Fix styling

* remove raw string type

* Update var/spack/repos/builtin/packages/py-pyside2/package.py

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

---------

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

var/spack/repos/builtin/packages/py-pyside2/package.py

@@ -54,7 +54,7 @@ class PyPyside2(PythonPackage):
     depends_on("cmake@3.1:", type="build")
     # libclang versioning from sources/shiboken2/doc/gettingstarted.rst
     depends_on("llvm@6", type="build", when="@5.12:5.13")
-    depends_on("llvm@10", type="build", when="@5.15")
+    depends_on("llvm@10:", type="build", when="@5.15:")
     depends_on("py-setuptools", type="build")
     depends_on("py-packaging", type="build")
     depends_on("py-wheel", type="build")
@@ -69,6 +69,23 @@ class PyPyside2(PythonPackage):
     depends_on("libxslt@1.1.19:", when="+doc", type="build")
     depends_on("py-sphinx", when="+doc", type="build")
 
+    def patch(self):
+        filter_file(
+            "=${shiboken_include_dirs}",
+            ":".join(
+                [
+                    "=${shiboken_include_dirs}",
+                    self.spec["qt"]["glx"]["libglx"].prefix.include,
+                    self.spec["qt"]["libxcb"].prefix.include,
+                ]
+            ),
+            "sources/pyside2/cmake/Macros/PySideModules.cmake",
+            string=True,
+        )
+
+    def setup_build_environment(self, env):
+        env.set("LLVM_INSTALL_DIR", self.spec["llvm"].prefix)
+
     def install_options(self, spec, prefix):
         args = [
             "--parallel={0}".format(make_jobs),