Update to latest x/tools

[tpounds]

Updates to latest x/tools to fix issues with some vet analyzers (see: #915), installing via go get, and running with Go 1.14.x (see: #893).

[jirfag]

Did you measure slowdown because of not including fixes in golangci/tools?

[ernado]

I've rebased and checked for performance regressions.

Branch:

INFO File cache stats: 137 entries of total size 2.5MiB 
INFO Memory: 429 samples, avg is 2344.3MB, max is 4132.5MB 
INFO Execution took 54.096474958s                 
Command exited with non-zero status 1
	Command being timed: "/src/golangci-lint/dist/golangci-lint_linux_amd64/golangci-lint run --disable unused --timeout 1h --verbose"
	User time (seconds): 528.70
	System time (seconds): 10.16
	Percent of CPU this job got: 992%
	Elapsed (wall clock) time (h:mm:ss or m:ss): 0:54.27
	Average shared text size (kbytes): 0
	Average unshared data size (kbytes): 0
	Average stack size (kbytes): 0
	Average total size (kbytes): 0
	Maximum resident set size (kbytes): 4183268
	Average resident set size (kbytes): 0
	Major (requiring I/O) page faults: 708
	Minor (reclaiming a frame) page faults: 1104224
	Voluntary context switches: 834066
	Involuntary context switches: 155082
	Swaps: 0
	File system inputs: 271448
	File system outputs: 130624
	Socket messages sent: 0
	Socket messages received: 0
	Signals delivered: 0
	Page size (bytes): 4096
	Exit status: 1

v1.23.3

INFO File cache stats: 140 entries of total size 2.5MiB 
INFO Memory: 424 samples, avg is 2369.1MB, max is 3731.2MB 
INFO Execution took 53.467114645s                 
Command exited with non-zero status 1
	Command being timed: "/src/golangci-lint/bin/golangci-lint run --disable unused --timeout 1h --verbose"
	User time (seconds): 529.55
	System time (seconds): 9.77
	Percent of CPU this job got: 1003%
	Elapsed (wall clock) time (h:mm:ss or m:ss): 0:53.73
	Average shared text size (kbytes): 0
	Average unshared data size (kbytes): 0
	Average stack size (kbytes): 0
	Average total size (kbytes): 0
	Maximum resident set size (kbytes): 3792600
	Average resident set size (kbytes): 0
	Major (requiring I/O) page faults: 168
	Minor (reclaiming a frame) page faults: 969709
	Voluntary context switches: 842769
	Involuntary context switches: 146200
	Swaps: 0
	File system inputs: 40992
	File system outputs: 130656
	Socket messages sent: 0
	Socket messages received: 0
	Signals delivered: 0
	Page size (bytes): 4096
	Exit status: 1

Looks like no major differences except 10% maximum RAM usage increase.
Since there are no other objections it is LGTM.

I'm going to rebase and merge it if tests will be green.

[ernado]

I've re-visited open PR's for golang/tools:
golang/tools#156 (btw from our master branch of fork)
golang/tools#160

Seems like it was a lot of (~697) commits since then, so let's try upstream version.