The spec file does something like
  CFLAGS="$RPM_OPT_FLAGS -DPURE_TERMINFO" ./configure --prefix=/usr ...
This is a pain when it comes to porting to newer architectures when the
package has outdated config.sub and config.guess scripts (very common).

A simple change to
  CFLAGS="%{optflags} -DPURE_TERMINFO"
  %define optflags $CFLAGS
  %configure ...
  make
Note that the exact syntax is important in order to avoid a recursive
macro.