#cgo pkg-config: traildb does see traildb.h on build

[vmakhaev]

After installation traildb with brew, traildb-go does not build with error:

brew install traildb
brew install traildb/judy/judy libarchive pkg-config

# github.com/traildb/traildb-go
../../../../../github.com/traildb/traildb-go/tdb.go:6:10: fatal error: 'traildb.h' file not found
#include <traildb.h>
         ^
1 error generated.

I was able to workaround this only by adding CGO_CFLAGS env var:

export CGO_CFLAGS=-I/usr/local/Cellar/traildb/0.6/include

mac os

➜  ~ go version
go version go1.7.6 darwin/amd64

➜  ~ brew info traildb
traildb: stable 0.6 (bottled)