Fix Buildtime Race Condition

The `mv` in `SuperBuild` for `lasmerge` will copy `lasmerge` to a file
called `SuperBuild/install/bin` **not**
`SuperBuild/install/bin/lasmerge` when the `bin` folder has not been
created. This is the case when building with 2 jobs (`-j2`) so builds
fail when moving onto OpenCV which requires that `bin` be a directory.

* Change `mv` to more reliable `install` command for `lasmerge`.

Signed-off-by: Daniel Llewellyn <daniel@snapcraft.ninja>

SuperBuild/CMakeLists.txt

@@ -159,5 +159,5 @@ externalproject_add(lastools
     UPDATE_COMMAND    ""
     BUILD_IN_SOURCE 1
     BUILD_COMMAND     make -C LASlib -j${nproc} CXXFLAGS='-std=c++11' && make -C src -j${nproc} CXXFLAGS='-std=c++11' lasmerge
-    INSTALL_COMMAND   mv ${SB_SOURCE_DIR}/lastools/bin/lasmerge ${SB_INSTALL_DIR}/bin
+    INSTALL_COMMAND   install -m755 -D -t ${SB_INSTALL_DIR}/bin ${SB_SOURCE_DIR}/lastools/bin/lasmerge
 )