Update

drone.yml

     event: [ push, tag ]
   depends_on: [ clone, prepare ]
   environment:
-    MAKEFLAGS: -j 4
+    MAKEFLAGS: -j 2
     # https://wiki.debian.org/CrossCompiling#Building_with_dpkg-buildpackage
+    # https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html
+    # https://www.gnu.org/software/make/manual/html_node/Catalogue-of-Rules.html#Catalogue-of-Rules
     # addr2line ar as c++filt cpp cpp-6 dwp elfedit g++ g++-6 gcc gcc-6 gcc-ar gcc-ar-6 gcc-nm gcc-nm-6 gcc-ranlib gcc-ranlib-6 gcov gcov-6 gcov-dump gcov-dump-6 gcov-tool gcov-tool-6 gprof ld ld.bfd ld.gold nm objcopy objdump ranlib readelf size strings strip 
     BUILD_ARCH: amd64 armhf # amd64 arm64 armel armhf i386 mips mips64el mipsel powerpc ppc64el s390x
   commands:
       fi ;
       DESTDIR="dist" ;
       RELEASE_DIR="release" ;
-      SRC_DIR="$(pwd)" ;
       ARCHIVE_NAME="$${NAME}_$${VERSION}" ;
       ARCHIVE_ROOT="$${NAME}-$${VERSION}" ;
+      SRC_DIR="$(pwd)" ;
+
     - mkdir -p "$${RELEASE_DIR}" &&
       tar --exclude='./.*' --exclude='debian' --exclude="$${RELEASE_DIR}"
         --transform "s/\./$${ARCHIVE_ROOT}/" 
         -cJf "$${SRC_DIR}/$${RELEASE_DIR}/$${ARCHIVE_NAME}.orig.tar.xz" .
-    - for ARCH in $${BUILD_ARCH} ; do set -e
+
+    - for ARCH in $${BUILD_ARCH} ; do set -e ;
         echo " ░▒▓█ Building for $${ARCH} █▓▒░ " ;
         BUILD_DIR="$${SRC_DIR}/build/$${ARCH}/$${ARCHIVE_ROOT}" ;
         case "$${ARCH}" in 
           PREFIX="" ; 
         fi ;
         export CC="$${PREFIX}gcc" ;
+        export CXX="$${PREFIX}g++" ;
         export LD="$${PREFIX}ld" ;
         export STRIP="$${PREFIX}strip" ;
         export MAKEFLAGS="$${MAKEFLAGS}" ;
           export DEB_BUILD_OPTIONS="nocheck" ;
           apt-get -qy -o Dpkg::Use-Pty=0 build-dep -a $${ARCH} . ;
           dpkg-buildpackage -us -uc -a "$${ARCH}" &&
-          cp ../*.tar.xz ../*.deb ../*.dsc "$${RELEASE_DIR}/" &&
+          cp ../*.tar.xz ../*.deb ../*.dsc "$${SRC_DIR}/$${RELEASE_DIR}/" &&
           ls -la .. ;
           make clean ;
         else