Turning of C++ detection on latest alpha

[Samuel Meder]

I'm using the latest alpha libtool alpha (1.4d) and would like to be
able to turn of detection of the C++ compiler and preprocessor. I've
got a system where the C++ is present but doesn't work due to a
expired license, which breaks the libtool configure step. I do not
need any C++ support for the code I'm working on, so it would be nice
if I could just turn this of. I've tried disabling the CXX tag, but
that doesn't seem to affect the detection. I've looked through the
code but can't seem to figure out how to turn this of. Any
ideas? 

/Sam

PS. I'm willing to cook up a patch for this if it would be considered
for inclusion.