cmd/gc: fix export data for aggressive inlining.

cmd/gc: fix export data for aggressive inlining.

Export data was broken after revision 6b602ab487d6
when -l is specified at least 3 times: it makes the compiler
write out func (*T).Method() declarations in export data, which
is not supported.

Also fix the formatting of recover() in export data. It was
not treated like panic() and was rendered as "<node RECOVER>".

R=golang-dev, lvd, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/7067051