permits testing that the compiler emits error messages for
specific lines that match egrep regexps. The desired error
messages are expressed using comments of the form
// ERROR "regexp"
R=r
DELTA=90 (73 added, 8 deleted, 9 changed)
OCL=15513
CL=15566
fixedbugs/bug012.go is broken again but i left it where it is, with
the golden file not reflecting the breakage so it will be noticed
R=ken,gri
OCL=14073
CL=14073