gettext: unvendor libxml (#43622)

var/spack/repos/builtin/packages/gettext/package.py

@@ -68,13 +68,29 @@ class Gettext(AutotoolsPackage, GNUMirrorPackage):
     patch("nvhpc-export-symbols.patch", when="%nvhpc")
     patch("nvhpc-long-width.patch", when="%nvhpc")
 
-    # Apply this only where we know that the system libc is glibc, be very careful:
-    @when("@:0.21.0 target=ppc64le:")
     def patch(self):
+        # Apply this only where we know that the system libc is glibc, be very careful:
+        if self.spec.satisfies("@:0.21.0 target=ppc64le"):
             for fn in ("gettext-tools/gnulib-lib/cdefs.h", "gettext-tools/libgrep/cdefs.h"):
                 with open(fn, "w") as f:
                     f.write("#include <sys/cdefs.h>\n")
 
+        # From the configure script: "we don't want to use an external libxml, because its
+        # dependencies and their dynamic relocations have an impact on the startup time", well,
+        # *we* do.
+        filter_file(
+            "gl_cv_libxml_force_included=yes",
+            "gl_cv_libxml_force_included=no",
+            "libtextstyle/configure",
+            string=True,
+        )
+
+    def flag_handler(self, name, flags):
+        # this goes together with gl_cv_libxml_force_included=no
+        if name == "ldflags":
+            flags.append("-lxml2")
+        return (flags, None, None)
+
     @classmethod
     def determine_version(cls, exe):
         gettext = Executable(exe)