Ignore spurious errors in SBCL compilation.
Ignore errors in sb-grovel-unknown-constant-condition-p. An error is raised if `simple-condition-format-control` is a formatter functionand is is passed to `string`. This now mirrors `match-condition-p` which also ignores errors when comparing a simple condition to a string. Test added to test-utilities.script for this issue. Thanks to Eric Timmons for the fix.