test: use testlib (fourth 100)

test: use testlib (fourth 100)

X ,s;^// \$G (\$D/)?\$F\.go *$;// compile;g
X ,s;^// \$G (\$D/)?\$F\.go && \$L \$F\.\$A *$;// build;g
X ,s;^// \$G (\$D/)?\$F\.go && \$L \$F\.\$A && \./\$A\.out *$;// run;g
X ,s;^// errchk \$G( -e)? (\$D/)?\$F\.go *$;// errorcheck;g

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5673079