Pull build date directly from git

Remove dependency on `date -d` which does not work on MacOS.

https://github.com/jaegertracing/jaeger/pull/3876/files#r1010648458

Signed-off-by: Yuri Shkuro <github@ysh.us>

Makefile

@@ -43,7 +43,7 @@ IMPORT_LOG=.import.log
 
 GIT_SHA=$(shell git rev-parse HEAD)
 GIT_CLOSEST_TAG=$(shell git describe --abbrev=0 --tags)
-DATE=$(shell date -u -d @$(shell git show -s --format=%ct) +'%Y-%m-%dT%H:%M:%SZ')
+DATE=$(shell TZ=UTC0 git show --quiet --date='format-local:%Y-%m-%dT%H:%M:%SZ' --format="%cd")
 BUILD_INFO_IMPORT_PATH=$(JAEGER_IMPORT_PATH)/pkg/version
 BUILD_INFO=-ldflags "-X $(BUILD_INFO_IMPORT_PATH).commitSHA=$(GIT_SHA) -X $(BUILD_INFO_IMPORT_PATH).latestVersion=$(GIT_CLOSEST_TAG) -X $(BUILD_INFO_IMPORT_PATH).date=$(DATE)"