Compilers: make oneapi ifx version_regex tolerant to wrappers (#21742)

If a user creates a wrapper for the ifx binary called ifx_orig,
this causes the ifx --version command to produce:

$ ifx --version
ifx_orig (IFORT) 2021.1 Beta 20201113
Copyright (C) 1985-2020 Intel Corporation. All rights reserved.

The regex for ifx currently expects the output to begin with
"ifx (IFORT)..." so the wrapper would not be detected as ifx. This
PR removes the need for the static "ifx" string which allows wrappers
to be detected as ifx.

In general, the Intel compiler regexes do not include the invoked
executable name (i.e., ifort, icc, icx, etc.), so this is not
expected to cause any issues.

lib/spack/spack/compilers/oneapi.py

@@ -29,7 +29,7 @@ class Oneapi(Compiler):
     PrgEnv_compiler = 'oneapi'
 
     version_argument = '--version'
-    version_regex = r'(?:(?:oneAPI DPC\+\+ Compiler)|(?:ifx \(IFORT\))) (\S+)'
+    version_regex = r'(?:(?:oneAPI DPC\+\+ Compiler)|(?:\(IFORT\))) (\S+)'
 
     @property
     def verbose_flag(self):