Making Apache 1.3.9 results in the link time error "_memmove not found".  SunOS 4.1.x, of course, doesn't have "memmove" but needs "bcopy" instead.  The memmove was found in the "pcrelib/pcre.o" object file.  It looks like the way the PCRE stuff handles the memmove problem with SunOS is that it has some conditional code in "pcrelib/internal.h".  Here is a snippet of code from "pcrelib/internal.h":

/* To cope with SunOS4 and other systems that lack memmove() but have bcopy(),
define a macro for memmove() if USE_BCOPY is defined. */

#ifdef USE_BCOPY
#undef  memmove        /* some systems may have a macro */
#define memmove(a, b, c) bcopy(b, a, c)
#endif

It looks like USE_BCOPY never gets defined.  I fixed this in my case by sticking in a "#define USE_BCOPY" right before the #ifdef.  After that it compiled up just fine.  So it looks like you need to get USE_BCOPY to propigate down into "pcrelib/Makefile" under the appropriate situation.