fix missig directory

dev/libs/libmpc/ympbuild

@@ -27,6 +27,7 @@ build(){
 
 package(){
     make install -j`nproc`
+    mkdir -p ${DESTDIR}/etc/ld.so.conf.d/
     echo "/usr/lib64/libmpc/" > ${DESTDIR}/etc/ld.so.conf.d/libmpc.conf
 }