gmake parsing issue

Author: rok

r/inst/build_arrow_static.sh

@@ -114,7 +114,7 @@ ${CMAKE_WRAPPER} ${CMAKE} -DARROW_BOOST_USE_SHARED=OFF \
     -G "${CMAKE_GENERATOR:-Unix Makefiles}" \
     ${SOURCE_DIR}
 
-${CMAKE} --build . --target install -- -j $N_JOBS
+(unset MAKEFLAGS MFLAGS; ${CMAKE} --build . --target install -- -j "${N_JOBS}")
 
 if command -v sccache &> /dev/null; then
   echo "=== sccache stats after the build ==="