Using "-x ada" to test whether GCC supports a language like Ada only works if
GCC was configured with Ada support, but the Ada front-end wasn't installed (as
is usually the case with distribution supplied gcc's).  If GCC wasn't configured
with Ada support then attempts to compile Ada like this succeed (i.e. zero exit
code)!  Instead of using "-x ada", create a file with the appropriate contents
and suffix, and try compiling that instead.