based on the fact that the crash never seemed to have happened with default screen resolutions and also inspired by the only other getmem usage in the code I came up with this simple solution which seems to work just fine.
I do not understand why getmem seems to need this, but well - feel free to explain.
# Find the Lua library
#
IF(WIN32)
SET(LUA_DEFAULT lua.dll)
ELSE(WIN32)
IF(APPLE)
SET(LUA_DEFAULT lua)
ELSE(APPLE)
#locate the system's lua library
FIND_LIBRARY(LUA_DEFAULT NAMES lua51 lua5.1 lua-5.1 lua PATHS /lib /usr/lib /usr/local/lib /usr/pkg/lib)
IF(${LUA_DEFAULT} MATCHES "LUA_DEFAULT-NOTFOUND")
#UNSET(LUA_DEFAULT)
MESSAGE(FATAL_ERROR "Couldn't find Lua 5.1 library!")
ENDIF()
#remove the path (fpc doesn't like it - why?)
GET_FILENAME_COMPONENT(LUA_DEFAULT ${LUA_DEFAULT} NAME)
ENDIF(APPLE)
ENDIF(WIN32)
SET(LUA_LIBRARY ${LUA_DEFAULT} CACHE STRING "Lua library to link to; file name without path only!")
#UNSET(LUA_DEFAULT)