Feature request: support distcc and ccache (automatic --mode=compile)

[Jari]

[Please keep CC, I'm not in this list]

Libtool could automatically switch to --mode-compile when it
sees standard commands 'ccache' or 'distcc'. The Makefiles usually do
not include --mode=compile, because the CC is usually set to gcc, 
which libtool recognizes.

An example; libtool 1.5.10 compiling sqlite package under Cygwin:

    ...
    ccache gcc  -o lemon /usr/src/build/build/sqlite/sqlite-2.8.12/tool/lemon.c
    cp /usr/src/build/build/sqlite/sqlite-2.8.12/tool/lempar.c .
    cp /usr/src/build/build/sqlite/sqlite-2.8.12/src/parse.y .
    ./lemon parse.y
    ./libtool ccache gcc  -DOS_UNIX=0 -DOS_WIN=1 -DHAVE_USLEEP=1 -I. 
-I/usr/src/build/build/sqlite/sqlite-2.8.12/src -DNDEBUG -no-undefined 
-I/usr/generic -I/usr/win -c 
/usr/src/build/build/sqlite/sqlite-2.8.12/src/attach.c
    libtool: warning: cannot infer operation mode from `ccache'
    libtool: you must specify a MODE
    Try `libtool --help' for more information.
 
If order to fix this I would have to replace all $(LIBTOOL) references
in sqlite's Makefile.in. 

Perhaps libtool could recognize few more compilers?

Jari