make variables to build FIPS binary

[chaitra-mylarappachar]

Enabled passing FIPS_BUILD Make variable to build FIPS-compliant Go plugin binary.
When FIPS_BUILD is set, CGO_ENABLED, GOLANG_FIPS will be set to 1 while building Go binaries as per the guidelines here -
https://rndwiki-pro.its.hpecorp.net/display/HCSS/Building+fips+compliant+GoLang+binaries

This variable is set while building FIPS binaries from quake's CI jobs ( quake/script/ci-build)

echo "LINUX-ONLY: building ${BIN_NAME} at location ${dir}."
BIN_PATH=bundles/x86_64/linux/ && mkdir -p ${BIN_PATH}
(cd ${dir}; GOOS=$OS_LINUX make build FIPS_BUILD=1)

US63619: build FIPS compatible binaries - qcli, standalone TF

[anurag-shrivastav]

LGTM