CMakeLists.txt: Add FIREBASE_FLATC_CMAKE_COMMAND (#1103)

Author: dconeybe

CMakeLists.txt

@@ -524,13 +524,20 @@ else()
  set(ENV_COMMAND env -i PATH=${firebase_command_line_path})
  endif()
 
+ # The cmake executable to use when compiling flatc. Normally, the default
+ # value (finding cmake in the PATH) is fine; however, in cases where cmake is
+ # *not* in the PATH (e.g. when building from CLion using the Android
+ # toolchain) it must be specified via via this cache variable.
+ set(FIREBASE_FLATC_CMAKE_COMMAND "cmake" CACHE FILEPATH
+ "The cmake command to use when compiling flatc.")
+
  # Build flatc by invoking the cmake build, with only the flatc target.
  file(MAKE_DIRECTORY ${firebase_external_flatc_build_dir})
  add_custom_command(
  OUTPUT ${firebase_external_flatc}
  COMMAND cd ${firebase_external_flatc_build_dir} ${COMMAND_CONCAT}
- ${ENV_COMMAND} cmake ${FLATBUFFERS_SOURCE_DIR} ${COMMAND_CONCAT}
- ${ENV_COMMAND} cmake --build . --target flatc
+ ${ENV_COMMAND} ${FIREBASE_FLATC_CMAKE_COMMAND} ${FLATBUFFERS_SOURCE_DIR} ${COMMAND_CONCAT}
+ ${ENV_COMMAND} ${FIREBASE_FLATC_CMAKE_COMMAND} --build . --target flatc
  COMMENT "Building flatc (the FlatBuffer schema compiler)")
 
  # Add a target so that we can run the custom commands before the code build.