bashisms in configure

[Alessandro-Barbieri]

when using SHELL=/bin/dash and CONFIG_SHELL=/bin/dash I get this but the configure continue and I have build failure later

checking for MUNGE... yes                                                                                                                                                                                                                   
./configure: 6276: test: x-lmunge : unexpected operator                                                                                                                                                                                     
checking for munge.h... yes                                                                                           
checking for munge_encode in -lmunge... yes                                                                           
./configure: 6350: test: xtrue: unexpected operator                                                                                                                                                                                         
./configure: 6358: test: x: unexpected operator        
./configure: 6362: test: x: unexpected operator     
./configure: 6392: test: x: unexpected operator  
./configure: 6399: test: x: unexpected operator                                                                                                                                                                                             
./configure: 6406: test: x: unexpected operator                      

the following lines in the configure fail

if test "x$MUNGE_LIBS" == "x"; then
if test "x$WANT_MUNGE" == "xtrue"; then
if test "x$WANT_KEYFILE" == "xtrue"; then
if test "x$WANT_NOSEC" == "xtrue"; then
if test "x$MUNGE" == "xtrue"; then
if test "x$ENABLE_NULL_ENCRYPTION" == "xtrue"; then

replacing == with = in https://github.com/LLNL/LaunchMON/blob/master/config/x_ac_handshake.m4 should work