mariadb-c-client: fix location of libraries (#22873)

Override 'libs' property to search for expected library name:
default Spack implementation can only locate libraries if they
match the package name.

var/spack/repos/builtin/packages/mariadb-c-client/package.py

@@ -68,3 +68,9 @@ def url_for_version(self, version):
     def cmake_args(self):
         args = ['-DWITH_EXTERNAL_ZLIB=ON', '-DWITH_MYSQLCOMPAT=ON']
         return args
+
+    @property
+    def libs(self):
+        return find_libraries(
+            ['libmariadb'], root=self.prefix, recursive=True, shared=True
+        )