dpv(3): MFC r330943, r335264

r330943:
Fix bad error messages from dpv(3)

Before = dpv: <__func__>: posix_spawnp(3): No such file or directory
After = dpv: <path/cmd>: No such file or directory

Most notably, show the 2nd argument being passed to posix_spawnp(3)
so we know what path/cmd failed.

Also, we don't need to have "posix_spawnp(3)" in the error message
nor the function because that can [a] change and [b] traversed using
a debugger if necessary.

r335264:
Fix comparison between pointer and char literal

PR: misc/204252
Reported by: David Binderman <dcb314@hotmail.com>
Sponsored by: Smule, Inc.

MFC r274925: misc mdoc fixes.

MFC revisions 294860,294862,294892-294893,294922

r294860: Add keep_tite configuration option
r294862: Bump copyrights
r294892: Remove unused function prototype
r294893: Fix a crash if `-D' is used without `-t title'
r294922: Fix fatal warn when compiling under GCC 5.2.0

Approved by: re (marius)

MFC r293868: Default to en_US.ISO8859-1 if no locale

MFC SVN revisions 293340, 293379

r293340: Increase maximum buffer size for `-x cmd' value
r293379: Bump copyright

MFC r290275: Make figpar(3) types/macros [more] unique (s/fp_/figpar_/gi)

MFC r289790: dpv(3) merged to stable/10 before release/10.2.0

MFC r289793: Bump date/copyright after correcting HISTORY

MFC r283863:
Fix a debug statement. Only the callback function (performing the
incrementing of dpv_overall_oread) knows what its purpose is (and
often times it was bytes, not lines).

MFC r283975 (araujo):
Clean up unused variable and silence clang warnings.

MFC r274116:

Add new libraries/utilities for data throughput visualization.
dpv(3): dialog progress view library
dpv(1): stream data from stdin or multiple paths with dialog progress view
figpar(3): configuration file parsing library

MFC r274120, r274121, r274123, r274124, r274144, r274146, r274159, r274192,
r274203, r274209, r274226, r274270, and r274851: Fixes following r274116

Reviews: D714
Relnotes: New libdpv/libfigpar and dpv(1) utility
Reviewed by: jelischer, shurd
Discussed at: MeetBSD California 2014 Vendor/Dev Summit
Discussed on: -current
Thanks to: ngie, ian, jelischer, shurd, bapt

Add new libraries/utilities for data throughput visualization.
dpv(3): dialog progress view library
dpv(1): stream data from stdin or multiple paths with dialog progress view
figpar(3): configuration file parsing library

Reviews: D714
Reviewed by: jelischer, shurd
Discussed at: MeetBSD California 2014 Vendor/Dev Summit
Discussed on: -current
MFC after: 21 days
X-MFC-to: stable/10 stable/9