maint: improve syntax check for space around =

maint: improve syntax check for space around =

Laine Stump noted on IRC that syntax check wasn't flagging his
typo of 'i= 0'.  This fixes it.

* build-aux/bracket-spacing.pl: Tighten 'space around =' rule.
* src/storage/storage_backend.c
(virStorageBackendCreateExecCommand): Fix offenders.
* src/util/virnuma.c (virNumaGetDistances): Likewise.
* src/vbox/vbox_tmpl.c (vboxDomainSnapshotDeleteMetadataOnly)
(vboxNetworkGetXMLDesc): Likewise.
* src/xenapi/xenapi_driver.c (xenapiDomainLookupByName):
Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>