bump buildroot to 2019.02.2

bsp/buildroot/package/go/go.hash

@@ -1,3 +1,3 @@
 # From https://golang.org/dl/
-sha256	bc1ef02bb1668835db1390a2e478dcbccb5dd16911691af9d75184bbe5aa943e  go1.11.5.src.tar.gz
+sha256	a96da1425dcbec094736033a8a416316547f8100ab4b72c31d4824d761d3e133  go1.11.6.src.tar.gz
 sha256	2d36597f7117c38b006835ae7f537487207d8ec407aa9d9980794b2030cbc067  LICENSE

bsp/buildroot/package/go/go.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-GO_VERSION = 1.11.5
+GO_VERSION = 1.11.6
 GO_SITE = https://storage.googleapis.com/golang
 GO_SOURCE = go$(GO_VERSION).src.tar.gz
 
@@ -37,13 +37,16 @@ GO_GOARCH = mips64le
 endif
 
 HOST_GO_DEPENDENCIES = host-go-bootstrap
+HOST_GO_HOST_CACHE = $(HOST_DIR)/usr/share/host-go-cache
 HOST_GO_ROOT = $(HOST_DIR)/lib/go
+HOST_GO_TARGET_CACHE = $(HOST_DIR)/usr/share/go-cache
 
 # For the convienience of target packages.
 HOST_GO_TOOLDIR = $(HOST_GO_ROOT)/pkg/tool/linux_$(GO_GOARCH)
 HOST_GO_TARGET_ENV = \
 	GO111MODULE=off \
 	GOARCH=$(GO_GOARCH) \
+	GOCACHE="$(HOST_GO_TARGET_CACHE)" \
 	GOROOT="$(HOST_GO_ROOT)" \
 	CC="$(TARGET_CC)" \
 	CXX="$(TARGET_CXX)" \
@@ -63,6 +66,7 @@ endif
 # HOSTCC_NOCCACHE.  See https://github.com/golang/go/issues/11685.
 HOST_GO_MAKE_ENV = \
 	GO111MODULE=off \
+	GOCACHE=$(HOST_GO_HOST_CACHE) \
 	GOROOT_BOOTSTRAP=$(HOST_GO_BOOTSTRAP_ROOT) \
 	GOROOT_FINAL=$(HOST_GO_ROOT) \
 	GOROOT="$(@D)" \