Make Posix compliant; fix RoboStack/ros-noetic#122

Author: Tobias-Fischer

vinca/templates/activate.sh.in

@@ -7,7 +7,7 @@
 # Not sure if this is necessary on UNIX?
 # export QT_PLUGIN_PATH=$CONDA_PREFIX\plugins
 
-if [ "$CONDA_BUILD" == "1" -a "$target_platform" != "$build_platform" ]; then
+if [ "$CONDA_BUILD" = "1" -a "$target_platform" != "$build_platform" ]; then
     # ignore sourcing
     echo "Not activating ROS when cross-compiling";
 else