Adjust the pkg-config file path since the port puts the shared libs in a sub directory.

Index: support-files/CMakeLists.txt
--- support-files/CMakeLists.txt.orig
+++ support-files/CMakeLists.txt
@@ -109,7 +109,7 @@ IF(UNIX AND NOT WITHOUT_SERVER)
   ENDIF()
 
   CONFIGURE_FILE(mariadb.pc.in ${CMAKE_CURRENT_BINARY_DIR}/mariadb.pc @ONLY)
-  INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/mariadb.pc DESTINATION ${INSTALL_LIBDIR}/pkgconfig COMPONENT Development)
+  INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/mariadb.pc DESTINATION ${INSTALL_LIBDIR}/../pkgconfig COMPONENT Development)
 
   INSTALL(FILES mysql.m4 DESTINATION ${INSTALL_SHAREDIR}/aclocal COMPONENT Development)
   
