Do not hardcode PKG_CONFIG_PATH in config.m4

Lookup whether libmapi include,libdir are found in configure

php/config.m4

@@ -5,16 +5,19 @@ PHP_MAPI_H="php_mapi.h mapi_exception.h mapi_profile_db.h mapi_profile.h mapi_se
 PHP_MAPI_SRC="mapi.c mapi_exception.c mapi_profile_db.c mapi_profile.c  mapi_session.c mapi_mailbox.c  mapi_folder.c mapi_message.c  mapi_contact.c mapi_task.c  mapi_appointment.c  mapi_attachment.c mapi_table.c mapi_message_table.c mapi_folder_table.c mapi_attachment_table.c php_mapi_constants.c "
 dnl remove php_mapi_constants.c when it is genration is included in the build
 
-if test "$PHP_MAPI" = "yes"; then
-  AC_DEFINE(HAVE_MAPI, 1, [Whether you have LibMapi ])
-  PHP_NEW_EXTENSION(openchange, $PHP_MAPI_SRC, $ext_shared)
-fi
+AC_DEFINE(HAVE_MAPI, 1, [Whether you have LibMapi ])
+PHP_NEW_EXTENSION(openchange, $PHP_MAPI_SRC, $ext_shared)
+
+LIBMAPI_INCLINE=`pkg-config --cflags libmapi`
+LIBMAPI_LIBLINE=`pkg-config --libs libmapi`
 
-PHP_ARG_WITH(pkgconfig-path, path to libmapi pkgconfig directory,
-[  --with-pkgconfig-path Path to libmapi pkgconfig directory], /usr/local/samba/lib/pkgconfig)
+if test x"$LIBMAPI_INCLINE" = x""; then
+   AC_MSG_ERROR([libmapi not found])
+fi
 
-LIBMAPI_INCLINE=`PKG_CONFIG_PATH=/opt/samba4/lib/pkgconfig pkg-config --cflags libmapi`
-LIBMAPI_LIBLINE=`PKG_CONFIG_PATH=/opt/samba4/lib/pkgconfig pkg-config --libs libmapi`
+if test x"$LIBMAPI_LIBLINE" = x""; then
+   AC_MSG_ERROR([libmapi not found])
+fi
 
 LDFLAGS="$LDFLAGS $LIBMAPI_LIBLINE"
 INCLUDES="$INCLUDES $LIBMAPI_INCLINE -I$PHP_OPENCHANGE_PATH -I$PHP_OPENCHANGE_PATH/utils"