mpg123: needs host-pkgconf

SDL detection is done using pkg-config.

Fixes http://autobuild.buildroot.net/results/437/437f408122d7f21420a7cdc9758caf0ab1ba877d/

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mpg123/mpg123.mk

@@ -11,6 +11,7 @@ MPG123_CONF_OPTS = --disable-lfs-alias
 MPG123_INSTALL_STAGING = YES
 MPG123_LICENSE = LGPLv2.1
 MPG123_LICENSE_FILES = COPYING
+MPG123_DEPENDENCIES = host-pkgconf
 
 MPG123_CPU = $(if $(BR2_SOFT_FLOAT),generic_nofpu,generic_fpu)