Vendor pre-built librdkafka (v0.11.3) under clib dir and use it when building

Author: nichegriffy

kafka/build.go

@@ -0,0 +1,15 @@
+package kafka
+
+// NOTE(griffy): 
+// We are simplifying how this package is built in a few ways for our own purposes:
+// 1) Pre-built releases of librdkafka are vendored under the `clib` directory which we link against without the usage of pkg-config
+// 2) The build tags (`static` and `static_all`) are removed in favor of the following default behavior:
+//    - For Linux, librdkafka is statically linked using the included pre-built package file while its (stripped down) dependencies are not (this corresponds to the previous `static` build tag)
+//    - For Mac, librdkafka is dynamically linked using the pre-built package file
+// The goal with these changes is that a single `go get` will be all that is needed to get up and running.
+
+// #cgo linux CFLAGS: -I${SRCDIR}/clib/include
+// #cgo linux LDFLAGS: -L${SRCDIR}/clib/lib -Wl,-Bstatic -lrdkafka -Wl,-Bdynamic -lpthread -lrt -ldl
+// #cgo darwin CFLAGS: -I${SRCDIR}/clib/include
+// #cgo darwin LDFLAGS: -L${SRCDIR}/clib/lib -Wl,-rpath,\$ORIGIN/vendor/github.com/nicheinc/confluent-kafka-go/kafka/clib/lib -lrdkafka
+import "C"

kafka/build_dynamic.go

@@ -1,3 +1,4 @@
+// +build ignore
 // +build !static
 // +build !static_all
 

kafka/build_static.go

@@ -1,3 +1,4 @@
+// +build ignore
 // +build static
 // +build !static_all
 

kafka/build_static_all.go

@@ -1,3 +1,4 @@
+// +build ignore
 // +build !static
 // +build static_all