Some systems require unusual options for compilation or linking that the `configure' script does not know about. You can give `configure' initial values for variables by setting them in the environment. Using a Bourne-compatible shell, you can do that on the command line like this: CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure

Or on systems that have the `env' program, you can do it like this: env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure