#1 Check to see if user supplied compiler is valid

[Sam Tuke]

Currently it is hard to diagnose compiler issues when using scons as no checks are performed to see if the user supplied compiler is valid before checking to see if it has OpenMP support. Therefore error messages relating to OpenMP could easily in fact be cause by the fact that the compiler cannot be located, and be unrelated to OpenMP.

Adding the following test at line 63 would provide a simple test to give feedback if the compiler doesn't exist:

if not os.path.exists(GetOption('cxx')):
print "User specified compiler binary could not be found; did you supply a complete path?"

Thanks,

Sam.