SIGSEGV in threadpool destructor

[ear7h]

Nevermind the cert errors... One thing to note is that the program counter is the same as the address for the violation.

root@f67ffc904246:/go/src/github.com/go-spatial/go-mbgl# go test -v --run=rSnapshot/1 ./mbgl/
=== RUN   TestSnapshotterSnapshot
=== RUN   TestSnapshotterSnapshot/1
new ptr 0x206c9b0
[INFO] {Map Snapshotter}[General]: GPU Identifier: Gallium 0.4 on llvmpipe (LLVM 3.9, 256 bits)
[ERROR] {Map Snapshotter}[Setup]: loading style failed: Problem with the SSL CA cert (path? access rights?): error setting certificate verify locations:
  CAfile: ca-bundle.crt
  CApath: /etc/ssl/certs
errProblem with the SSL CA cert (path? access rights?): error setting certificate verify locations:
  CAfile: ca-bundle.crt
  CApath: /etc/ssl/certs
old ptr 0x206c9b0
fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x1 addr=0xa1 pc=0xa1]

runtime stack:
runtime.throw(0xe7b679, 0x2a)
	/usr/local/go/src/runtime/panic.go:608 +0x72
runtime.sigpanic()
	/usr/local/go/src/runtime/signal_unix.go:374 +0x2f2

goroutine 20 [syscall, locked to thread]:
runtime.cgocall(0x68d340, 0xc00003dd30, 0x5c4b36)
	/usr/local/go/src/runtime/cgocall.go:128 +0x5e fp=0xc00003dd00 sp=0xc00003dcc8 pc=0x571c2e
github.com/go-spatial/go-mbgl/mbgl._Cfunc_mbgl_thread_pool_destruct(0x206c9b0)
	_cgo_gotypes.go:856 +0x41 fp=0xc00003dd30 sp=0xc00003dd00 pc=0x6886c1
github.com/go-spatial/go-mbgl/mbgl.(*ThreadPool).Destruct(0x206c9b0)
	/go/src/github.com/go-spatial/go-mbgl/mbgl/thread_pool.go:27 +0x2b fp=0xc00003dd48 sp=0xc00003dd30 pc=0x689b6b
runtime.call32(0x0, 0xe7d060, 0xc00008c7f0, 0x800000008)
	/usr/local/go/src/runtime/asm_amd64.s:522 +0x3b fp=0xc00003dd78 sp=0xc00003dd48 pc=0x5c4b7b
runtime.Goexit()
	/usr/local/go/src/runtime/panic.go:397 +0xef fp=0xc00003ddc0 sp=0xc00003dd78 pc=0x5988ff
testing.(*common).FailNow(0xc0000d8200)
	/usr/local/go/src/testing/testing.go:590 +0x39 fp=0xc00003ddd8 sp=0xc00003ddc0 pc=0x6235c9
testing.(*common).Fatalf(0xc0000d8200, 0xe768d2, 0x13, 0xc00003dec0, 0x1, 0x1)
	/usr/local/go/src/testing/testing.go:634 +0x83 fp=0xc00003de20 sp=0xc00003ddd8 pc=0x6238a3
github.com/go-spatial/go-mbgl/mbgl.TestSnapshotterSnapshot.func1(0xe96f20, 0x206b3b0, 0xe7b38d, 0x29, 0x6400000064, 0x0, 0x3f800000, 0x0, 0x0, 0x0, ...)
	/go/src/github.com/go-spatial/go-mbgl/mbgl/map_snapshotter_test.go:112 +0x369 fp=0xc00003df40 sp=0xc00003de20 pc=0x68a449
github.com/go-spatial/go-mbgl/mbgl.TestSnapshotterSnapshot.func2(0xc0000d8200)
	/go/src/github.com/go-spatial/go-mbgl/mbgl/map_snapshotter_test.go:131 +0x4a fp=0xc00003dfa8 sp=0xc00003df40 pc=0x68a6da
testing.tRunner(0xc0000d8200, 0xc000094080)
	/usr/local/go/src/testing/testing.go:827 +0xbf fp=0xc00003dfd0 sp=0xc00003dfa8 pc=0x623baf
runtime.goexit()
	/usr/local/go/src/runtime/asm_amd64.s:1333 +0x1 fp=0xc00003dfd8 sp=0xc00003dfd0 pc=0x5c6891
created by testing.(*T).Run
	/usr/local/go/src/testing/testing.go:878 +0x353

goroutine 1 [chan receive]:
testing.(*T).Run(0xc0000d8100, 0xe77659, 0x17, 0xe7d0f0, 0x5d8a01)
	/usr/local/go/src/testing/testing.go:879 +0x37a
testing.runTests.func1(0xc0000d8000)
	/usr/local/go/src/testing/testing.go:1119 +0x78
testing.tRunner(0xc0000d8000, 0xc0000a5e08)
	/usr/local/go/src/testing/testing.go:827 +0xbf
testing.runTests(0xc000094040, 0x16940e0, 0xd, 0xd, 0x57a7ef)
	/usr/local/go/src/testing/testing.go:1117 +0x2aa
testing.(*M).Run(0xc0000b6000, 0x0)
	/usr/local/go/src/testing/testing.go:1034 +0x165
main.main()
	_testmain.go:68 +0x13d

goroutine 19 [chan receive]:
testing.(*T).Run(0xc0000d8200, 0xe738ca, 0x1, 0xc000094080, 0xc00005ab08)
	/usr/local/go/src/testing/testing.go:879 +0x37a
github.com/go-spatial/go-mbgl/mbgl.TestSnapshotterSnapshot(0xc0000d8100)
	/go/src/github.com/go-spatial/go-mbgl/mbgl/map_snapshotter_test.go:130 +0x19b
testing.tRunner(0xc0000d8100, 0xe7d0f0)
	/usr/local/go/src/testing/testing.go:827 +0xbf
created by testing.(*T).Run
	/usr/local/go/src/testing/testing.go:878 +0x353
FAIL	github.com/go-spatial/go-mbgl/mbgl	0.245s