MIPSPro and the predecessor compiler which was part of the IDO (IRIS
Development Option) were only ever shipped on the SGI IRIX operating
system (with MIPSPro on 6.0+ which was released in 1994). Limit the
autoconf check to IRIX when probing for these compilers to save some
cycles on other platforms.
Closes: #13611
Reviewed-by: Daniel Stenberg <daniel@haxx.se>
91908f66ad