MOLA CMake functions

The following CMake functions are defined by mola-common.

find_mola_package()

# find_mola_package(package_name)
#
# Does nothing if the target is known at build time, or issues the corresponding
# standard CMake find_package().

mola_add_executable()

# mola_add_executable(
#   TARGET name
#   SOURCES ${SRC_FILES}
#   [LINK_LIBRARIES lib1 lib2]
#   )
#
# Defines a MOLA executable

mola_add_library()

# mola_add_library(
#   TARGET name
#   SOURCES ${SRC_FILES}
#   [PUBLIC_LINK_LIBRARIES lib1 lib2 ...]
#   [PRIVATE_LINK_LIBRARIES lib3 lib4 ...]
# [CMAKE_DEPENDENCIES dep1 dep2...]
#   )
#
# Defines a MOLA library. CMAKE_DEPENDENCIES enumerates those cmake packages
# that must be find_package()'d in this library's xxx-config.cmake script.

mola_find_package_or_return()

# mola_find_package_or_return(package_name)
#
# Calls find_package(package_name QUIET), and if it is not found, prints a
# descriptive message and call "return()" to exit the current cmake script.