abuild: convert -{alpha,beta,rc,pre} version suffixes from pkgconf

convert version suffixes in pkgconf modversion to something apk
can deal with.

abuild.in

@@ -1091,7 +1091,7 @@ prepare_pkgconfig_provides() {
 		fi
 		local f=${i##*/}
 		local v=$(PKG_CONFIG_PATH="$dir"/usr/lib/pkgconfig PKG_CONFIG_MAXIMUM_TRAVERSE_DEPTH=1 pkg-config \
-			--modversion ${f%.pc})
+			--modversion ${f%.pc} | sed -E -e 's/-(alpha|beta|rc|pre)/_\1/')
 		$APK version --check --quiet $v || die "$i: pkgconf version $v is invalid"
 		echo "$pcprefix${f%.pc}=${v:-0}" >> "$controldir"/.provides-pc
 	done