make autogenerated functions to be 'static inline' instead of 'inline'

This fixes link issue and compile warning, for more details about this
issue look at
https://bitbucket.org/mjsousa/matiec/issues/53/c-compiler-warning-if-iec-function-is-used

AM_CXXFLAGS = -g -Wall -Wpointer-arith -Wwrite-strings -Wno-unused