Fixed emacs_mode build with cross-filesystem builds.
Fixed emacs_mode build with cross-filesystem builds.

If the source code and the build directory
are on different file systems, the previous
build script for emacs_mode would fail.

This commit fixes that issue.

avisparesearch/Mozart2,eregon/mozart2,yjaradin/mozart2,avisparesearch/Mozart2,eregon/mozart2,yjaradin/mozart2,Angeldude/mozart2,dianacgr/mozart2,dianacgr/mozart2,layus/mozart2,Angeldude/mozart2,layus/mozart2,eregon/mozart2,yjaradin/mozart2,Angeldude/mozart2,mozart/mozart2,mozart/mozart2,dianacgr/mozart2,layus/mozart2,mozart/mozart2