Be able to switch-off ASAN builds of our binaries.

Inroduce a way to not take a 2x performance hit when testing. It
is of importance if we run with hundreds of BTSes and 10k+ subscribers.
In the absence of using getops or shflags use an environment for it.

Change-Id: I540ba1c35e8fb72abcee0d86e0bdc1136b47345c
diff --git a/contrib/jenkins-build-osmocom-bb.sh b/contrib/jenkins-build-osmocom-bb.sh
index e968a1a..827fc94 100755
--- a/contrib/jenkins-build-osmocom-bb.sh
+++ b/contrib/jenkins-build-osmocom-bb.sh
@@ -8,9 +8,9 @@
 FW_RPM_URL="http://download.opensuse.org/repositories/home:/mnhauke:/osmocom:/nightly/SLE_15/x86_64/"
 
 build_repo libosmocore --disable-doxygen
-build_repo_dir osmocom-bb src/host/virt_phy --enable-sanitize
-build_repo_dir osmocom-bb src/host/osmocon --enable-sanitize
-build_repo_dir osmocom-bb src/host/layer23 --enable-sanitize
+build_repo_dir osmocom-bb src/host/virt_phy ${SANITIZE_FLAGS}
+build_repo_dir osmocom-bb src/host/osmocon ${SANITIZE_FLAGS}
+build_repo_dir osmocom-bb src/host/layer23 ${SANITIZE_FLAGS}
 
 mkdir -p "$prefix"
 cd "$prefix"