OSHMEM/CONFIGURE: verbs component - restore the previous build behavior

In case where support was requested but not found, stop the build.

Signed-off-by: Alina Sklarevich <alinas@mellanox.com>

oshmem/mca/sshmem/verbs/configure.m4

@@ -110,7 +110,8 @@ AC_DEFUN([MCA_oshmem_sshmem_verbs_CONFIG],[
     AC_DEFINE_UNQUOTED(MPAGE_HAVE_IBV_EXP_REG_MR_CREATE_FLAGS, $exp_reg_mr_happy, [create_flags field is part of ibv_exp_reg_mr_in])
 
     AS_IF([test "$enable_verbs_sshmem" = "yes" && test "$oshmem_verbs_sm_build_verbs" = "0"],
-          [AC_MSG_WARN([VERBS shared memory support requested but not found])])
+          [AC_MSG_WARN([VERBS shared memory support requested but not found])
+           AC_MSG_ERROR([Cannot continue])])
 
     AS_IF([test "$oshmem_verbs_sm_build_verbs" = "1"], [$1], [$2])