pngcheck: Explicitly set EXTRA_OEMAKE as required

This recipe currently relies on EXTRA_OEMAKE having been to set to "-e
MAKEFLAGS=" in bitbake.conf to operate. It is necessary to make this
explicit so that the default in bitbake.conf can be changed.

Signed-off-by: Mike Crowe <mac@mcrowe.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-oe/recipes-support/pngcheck/pngcheck_2.3.0.bb

@@ -9,6 +9,8 @@ SRC_URI = "${SOURCEFORGE_MIRROR}/project/png-mng/${BPN}/${PV}/${BPN}-${PV}.tar.g
 SRC_URI[md5sum] = "980bd6d9a3830fdce746d7fe3c9166ee"
 SRC_URI[sha256sum] = "77f0a039ac64df55fbd06af6f872fdbad4f639d009bbb5cd5cbe4db25690f35f"
 
+EXTRA_OEMAKE = "-e MAKEFLAGS="
+
 do_compile() {
     oe_runmake -f Makefile.unx INCS=-I${STAGING_DIR_HOST}${incdir} LIBS=${STAGING_DIR_HOST}${libdir}/libz.a
 }
@@ -19,4 +21,3 @@ do_install() {
     install png-fix-IDAT-windowsize ${D}${bindir}
     install pngsplit ${D}${bindir}
 }
-