hdf5: fix showconfig (#34920)

Co-authored-by: Bernhard Kaindl <43588962+bernhardkaindl@users.noreply.github.com>

var/spack/repos/builtin/packages/hdf5/package.py

@@ -686,6 +686,24 @@ def fix_package_config(self):
                     if not os.path.exists(tgt_filename):
                         symlink(src_filename, tgt_filename)
 
+    @run_after("install")
+    def fix_showconfig(self):
+        # The 'Extra libraries' entry of the 'h5cc -showconfig' command is a space-separated list
+        # of linker flags if the package is installed with Autotools, and a semicolon-separated
+        # list of library names if the package is installed with CMake. There are use cases that
+        # rely on the old Autotools behavior. Here, we make sure that the output of the command
+        # looks like it was before we switch to CMake.
+        filter_file(
+            r"^(\s*Extra libraries: )(.*)",
+            lambda match: "{0}{1}".format(
+                match.group(1),
+                " ".join("-l{0}".format(name) for name in filter(None, match.group(2).split(";"))),
+            ),
+            self.prefix.lib.join("libhdf5.settings"),
+            backup=False,
+            ignore_absent=True,
+        )
+
     @run_after("install")
     @on_package_attributes(run_tests=True)
     def check_install(self):