efreet: fix build error by using PACKAGE_SYSCONF_DIR

This patch fixes build error of make build by applying
0d7f20bbc6.

meson build defines PACKAGE_SYSCONF_DIR so there is no build error but
make build did not define it.

src/Makefile_Efreet.am

@@ -12,6 +12,7 @@ EFREET_COMMON_CPPFLAGS = -I$(top_builddir)/src/lib/efl \
 -DPACKAGE_DATA_DIR=\"$(datadir)/efreet\" \
 -DPACKAGE_BUILD_DIR=\"$(abs_top_builddir)\" \
 -DPACKAGE_SRC_DIR=\"$(abs_top_srcdir)\" \
+-DPACKAGE_SYSCONF_DIR=\"$(sysconfdir)\" \
 -DDATA_DIR=\"$(datadir)\" \
 -DLOCALE_DIR=\"@LOCALE_DIR@\" \
 @EFREET_CFLAGS@