sh: read more profile files.

Differential Revision: https://reviews.freebsd.org/D36505
MFC after: 1 month

(cherry picked from commit 497cdf9673ec53d59634bb78862cd8dea3d5c155)

sh: when loading profile, skip obvious scratch files.

Differential Revision: https://reviews.freebsd.org/D36856

(cherry picked from commit d3890a547d201d1f5043e51baa406ac9d5d3a60a)

sh: when loading profile, read only .sh files.

Reviewers: jilles, eugen_grosbein.net, cy

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D37034

(cherry picked from commit 8d7221ca2dd5e0b6c633761b314cffed82ddca72)
(cherry picked from commit 4ea49af3afe127c424a1b843617225fd437b51d1)

Approved by: re (gjb)