Parallel compilation flags in package scripts

package_scripts/compile_static_boost.sh

@@ -5,4 +5,4 @@
 # on libicu, which is unneeded and would require then linking the mex
 # module with it as well.  We just stage instead of install, then the
 # toolbox_package_unix.sh script uses the staged boost.
-./b2 link=static threading=multi cxxflags=-fPIC cflags=-fPIC --disable-icu -a stage
+./b2 link=static threading=multi cxxflags=-fPIC cflags=-fPIC --disable-icu -a -j4 stage

package_scripts/toolbox_package_unix.sh

@@ -54,7 +54,7 @@ if [ ! $? ]; then
 fi
 
 # Compile
-make -j8 install
+make -j4 install
 
 # Create package
 tar czf gtsam-toolbox-2.3.0-$platform.tgz -C stage/borg toolbox