maint: fix grammar errors

maint: fix grammar errors

Jim Meyering recently improved gnulib to catch various grammar
errors during 'make syntax-check'.

* .gnulib: Update to latest, for syntax-check improvements.
* include/libvirt/libvirt.h.in (virConnectAuthCallbackPtr): Use
cannot rather than two words.
* src/driver.c: Likewise.
* src/driver.h (VIR_SECRET_GET_VALUE_INTERNAL_CALL): Likewise.
* src/remote/remote_driver.c (initialize_gnutls): Likewise.
* src/util/pci.c (pciBindDeviceToStub): Likewise.
* src/storage/storage_backend.c (virStorageBackendCreateQemuImg):
Likewise.
(virStorageBackendUpdateVolTargetInfoFD): Avoid doubled word.
* docs/formatdomain.html.in: Likewise.
* src/qemu/qemu_process.c (qemuProcessStart): Likewise.
* cfg.mk (exclude_file_name_regexp--sc_prohibit_can_not)
(exclude_file_name_regexp--sc_prohibit_doubled_word): Exclude
existing translation problems.