Adds gitignore for Eclipse build

As the CMake CDT generator seems unmaintained and does not work anymore
with the current CDT version, Eclipse projects have to be created via
the Eclipse wizard, requiring a build folder in the same parent folder
as the source. This build folder is excluded from Git via this gitignore
file

Signed-off-by: Martin Melik-Merkumians <melik-merkumians@acin.tuwien.ac.at>

source/.gitignore

@@ -0,0 +1,2 @@
+/Debug/
+/build/