Description of problem:

Recent 'm4' creates a warning for patsubst expressions with the '?' 
pattern when result is empty

| $ echo 'patsubst(config.h,\([^:]*/\)?.*,\1)' | m4 -E ; echo $?
| stdin:1: m4: Warning: sub-expression 1 not present
| 1
| $

With 'm4-1.4.4' from FC-5, things are fine

| $ echo 'patsubst(config.h,\([^:]*/\)?.*,\1)' | m4 -E ; echo $?
|
| 0
| $


This causes real trouble when building old software which is using
automake-1.4. There, AM_CONFIG_HEADER() contains the pattern

| <<test -z "<<$>>CONFIG_HEADERS" || echo timestamp > patsubst(<<$1>>, <<^\([^:]*/\)?.*>>, <<\1>>)stamp-h<<>>dnl>>,                

and will trigger an error on e.g.

| AM_CONFIG_HEADER(config.h)


Version-Release number of selected component (if applicable):

m4-1.4.5-3