file D left after automake configure test

[Bob Proulx]

After running configure I notice that an empty file "D" is left around
as trash.  I investigated and and found the following.  This occures
on HP-UX using the native ANSI compiler and running the latest test
automake-1.4b and the new dependency tracking code.  The configure
script runs the following snippet:

  depmode=gcc source=conftest.c object=conftest.o depfile=conftest.Po 
tmpdepfile=conftest.TPo /bin/sh config/depcomp cc -c conftest.c -o conftest.o

This occurs inside the test that prints "checking dependency style".
Expanding on this a little by using sh -x:

  depmode=gcc source=conftest.c object=conftest.o depfile=conftest.Po 
tmpdepfile=conftest.TPo /bin/sh -x config/depcomp cc -c conftest.c -o conftest.o
+ test -z gcc
+ test -z conftest.c
+ test -z conftest.o
+ depfile=conftest.Po
+ tmpdepfile=conftest.TPo
+ rm -f conftest.TPo
+ test gcc = hp
+ test gcc = dashXmstdout
+ test -z 
+ gccflag=-MD,
+ cc -c conftest.c -o conftest.o -Wp,-MD,conftest.TPo
cpp: error 3: Too many arguments to cpp.
+ stat=1
+ rm -f conftest.TPo
+ exit 1

This leaves an empty file called "D" in the current directory.  I
don't know why it is testing for depmode=gcc with the native ANSI C
compiler.  I don't have gcc in my path and so it does not find one.  I
believe that to be the root of this problem.  This should be
depmode=hp instead of depmode=gcc for this configuration.

Checking the man page for cpp on hpux and I see the following:
:      -M[makefile]   Generates makefile dependencies and sends the results
:                     to the file makefile.  If the argument makefile is
:                     omitted, the result is sent to the standard error.

So everything is making sense.  -Wp passes option to cpp and the -M
option to cpp is sending dependencies to the file "D" and then
complaining that 'conftest.TPo' is too many arguments.  But the syntax
used was gcc syntax and a completely different result was expected.
If the depmode is set to hp then things work better here.

I should dig into this some more but this is where I am stopping for
the night and wanted to report this minor problem.  This appears to be
a spurious result as to all other intents and purposes everything
configures and works well from this point on.

BTW...  I like the new dependency code!  I can now swap between HP-UX
ANSI C and Linux GCC interchangeably.

Bob Proulx