apps/tools: support src/inc sub directory
apps/tools: support src/inc sub directory

If additional files are needed instead of the main source, the user can
add to the newly created subdirectory.

Change-Id: Ie0b2f616184576cc259b6ec338097553ac10b98e
Signed-off-by: Junhwan Park <7fee488b6f78fc50b291ffc7d10428788977e877@samsung.com>

JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT