Flip REPRODUCIBLE_BUILD back to off by default in head.

Having the full uname output can be useful on head even with
unmodified trees or trees that newvers.sh fails to recognize as
modified.

Reviewed by:	emaste
Differential Revision:	https://reviews.freebsd.org/D20895

share/mk/src.opts.mk

@@ -162,7 +162,6 @@ __DEFAULT_YES_OPTIONS = \
     QUOTAS \
     RADIUS_SUPPORT \
     RBOOTD \
-    REPRODUCIBLE_BUILD \
     RESCUE \
     ROUTED \
     SENDMAIL \
@@ -208,6 +207,7 @@ __DEFAULT_NO_OPTIONS = \
     LOADER_VERIEXEC_PASS_MANIFEST \
     OFED_EXTRA \
     OPENLDAP \
+    REPRODUCIBLE_BUILD \
     RPCBIND_WARMSTART_SUPPORT \
     SHARED_TOOLCHAIN \
     SORT_THREADS \