FindLAMMPS.cmake: add LAMMPS_API_DEFINES

cmake/FindLAMMPS.cmake.in

@@ -4,6 +4,7 @@
 # The following variables will set:
 #  LAMMPS_INCLUDE_DIRS - where to find lammps/library.h, etc.
 #  LAMMPS_LIBRARIES    - List of libraries when using lammps.
+#  LAMMPS_API_DEFINES  - lammps library api defines
 #  LAMMPS_VERSION      - lammps library version 
 #  LAMMPS_FOUND        - True if liblammps found.
 #
@@ -26,8 +27,9 @@ find_package(PkgConfig)
 pkg_check_modules(PC_LAMMPS liblammps@LAMMPS_LIB_SUFFIX@)
 find_path(LAMMPS_INCLUDE_DIR lammps/library.h HINTS ${PC_LAMMPS_INCLUDE_DIRS} @CMAKE_INSTALL_FULL_INCLUDEDIR@)
 
-# TODO figure out library version from header
+# TODO figure these out library version from header
 set(LAMMPS_VERSION 20180822)
+set(LAMMPS_API_DEFINES @LAMMPS_API_DEFINES@)
 
 find_library(LAMMPS_LIBRARY NAMES lammps@LAMMPS_LIB_SUFFIX@ HINTS ${PC_LAMMPS_LIBRARY_DIRS} @CMAKE_INSTALL_FULL_LIBDIR@)
 
@@ -43,5 +45,5 @@ mark_as_advanced(LAMMPS_INCLUDE_DIR LAMMPS_LIBRARY)
 
 if(LAMMPS_FOUND AND NOT TARGET LAMMPS::LAMMPS)
   add_library(LAMMPS::LAMMPS UNKNOWN IMPORTED)
-  set_target_properties(LAMMPS::LAMMPS PROPERTIES IMPORTED_LOCATION ${LAMMPS_LIBRARY} INTERFACE_INCLUDE_DIRECTORIES ${LAMMPS_INCLUDE_DIR})
+  set_target_properties(LAMMPS::LAMMPS PROPERTIES IMPORTED_LOCATION "${LAMMPS_LIBRARY}" INTERFACE_INCLUDE_DIRECTORIES "${LAMMPS_INCLUDE_DIR}" INTERFACE_COMPILE_DEFINITIONS "${LAMMPS_API_DEFINES}")
 endif()