lmdb: replace tag with commit id in SRCREV

Using tag in SRCREV does not work when the git source
is added to the PREMIRRORS and set BB_NO_NETWORK = "1".

This is because there is no SRCREV, and bitbake needs
check the original url to get it.

Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-dbs/lmdb/lmdb_0.9.29.bb

@@ -13,7 +13,7 @@ SRC_URI = "git://github.com/LMDB/lmdb.git;nobranch=1 \
            file://0001-Makefile-use-libprefix-instead-of-libdir.patch \
            "
 
-SRCREV = "LMDB_${PV}"
+SRCREV = "8ad7be2510414b9506ec9f9e24f24d04d9b04a1a"
 
 inherit base ptest