deptrack: avoid few forks in configure (minor optimization)

* m4/depend.m4 (_AM_DEPENDENCIES): Use 'echo > file' instead of
'touch file' to ensure the creation of a dummy file.  Adjust the
comment that explains why we can't simply use ': > file': the
problem this latter idiom tickles is present also with Solaris 10
/bin/sh, not merely with Solaris 8 /bin/sh.

diff --git a/m4/depend.m4 b/m4/depend.m4
index 9fbf438e19f54084772000cc60af4b3a0f53b178..1601c637ad80ed047fc9f217066f401fea29e5b3 100644 (file)
--- a/m4/depend.m4
+++ b/m4/depend.m4
@@ -85,8 +85,8 @@ AC_CACHE_CHECK([dependency style of $depcc],
     for i in 1 2 3 4 5 6; do
       echo '#include "conftst'$i'.h"' >> sub/conftest.c
       # Using ": > sub/conftst$i.h" creates only sub/conftst1.h with
-      # Solaris 8's {/usr,}/bin/sh.
-      touch sub/conftst$i.h
+      # Solaris 10 /bin/sh.
+      echo '/* dummy */' > sub/conftst$i.h
     done
     echo "${am__include} ${am__quote}sub/conftest.Po${am__quote}" > confmf