cmake: generated application version header when VERSION file is present

Allow applications to create a VERSION file in their application folder.

The presence of a VERSION file will create a app_version_h target which
generates an app_version.h file using same infrastructure as the Zephyr
kernel version.h generation.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

Author: tejlmand

CMakeLists.txt

@@ -552,6 +552,21 @@ add_custom_command(
 )
 add_custom_target(version_h DEPENDS ${PROJECT_BINARY_DIR}/include/generated/version.h)
 
+if(EXISTS ${APPLICATION_SOURCE_DIR}/VERSION)
+  add_custom_command(
+    OUTPUT ${PROJECT_BINARY_DIR}/include/generated/app_version.h
+    COMMAND ${CMAKE_COMMAND} -DZEPHYR_BASE=${ZEPHYR_BASE}
+      -DOUT_FILE=${PROJECT_BINARY_DIR}/include/generated/app_version.h
+      -DVERSION_TYPE=APP
+      -DVERSION_FILE=${APPLICATION_SOURCE_DIR}/VERSION
+      ${build_version_argument}
+      -P ${ZEPHYR_BASE}/cmake/gen_version_h.cmake
+    DEPENDS ${APPLICATION_SOURCE_DIR}/VERSION ${git_dependency}
+  )
+  add_custom_target(app_version_h DEPENDS ${PROJECT_BINARY_DIR}/include/generated/app_version.h)
+  add_dependencies(zephyr_interface app_version_h)
+endif()
+
 # Unfortunately, the order in which CMakeLists.txt code is processed
 # matters so we need to be careful about how we order the processing
 # of subdirectories. One example is "Compiler flags added late in the