Remove ALLOW_THREADLESS_LIBGIT2

This environment variable is to be used on the upstream
version that is yet to be merged. Until it is merged,
there is no point in keeping it here.

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

Author: Paulo Gomes

Dockerfile.test-libgit2-only

@@ -129,6 +129,5 @@ COPY --from=build \
     /root/smoketest/static-test-runner .
 
 ENV SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt
-ENV ALLOW_THREADLESS_LIBGIT2=true
 
 RUN /root/smoketest/static-test-runner

Makefile

@@ -22,7 +22,6 @@ export LIBRARY_PATH=$(LIBGIT2_LIB_PATH)
 export PKG_CONFIG_PATH=$(LIBGIT2_LIB_PATH)/pkgconfig
 export CGO_LDFLAGS=$(shell PKG_CONFIG_PATH=$(PKG_CONFIG_PATH) pkg-config --libs --static --cflags libgit2)
 export CGO_CFLAGS=-I$(LIBGIT2_PATH)/include
-export ALLOW_THREADLESS_LIBGIT2=true
 
 GO_STATIC_FLAGS=-tags 'netgo,osusergo,static_build'