option cutils: Fix and clean up number conversions

# gpg: Signature made Thu 23 Feb 2017 19:41:17 GMT
# gpg:                using RSA key 0x3870B400EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>"
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>"
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-util-2017-02-23: (24 commits)
  option: Fix checking of sizes for overflow and trailing crap
  util/cutils: Change qemu_strtosz*() from int64_t to uint64_t
  util/cutils: Return qemu_strtosz*() error and value separately
  util/cutils: Let qemu_strtosz*() optionally reject trailing crap
  qemu-img: Wrap cvtnum() around qemu_strtosz()
  test-cutils: Drop suffix from test_qemu_strtosz_simple()
  test-cutils: Use qemu_strtosz() more often
  util/cutils: Drop QEMU_STRTOSZ_DEFSUFFIX_* macros
  util/cutils: New qemu_strtosz()
  util/cutils: Rename qemu_strtosz() to qemu_strtosz_MiB()
  util/cutils: New qemu_strtosz_metric()
  test-cutils: Cover qemu_strtosz() around range limits
  test-cutils: Cover qemu_strtosz() with trailing crap
  test-cutils: Cover qemu_strtosz() invalid input
  test-cutils: Add missing qemu_strtosz()... endptr checks
  option: Fix to reject invalid and overflowing numbers
  util/cutils: Clean up control flow around qemu_strtol() a bit
  util/cutils: Clean up variable names around qemu_strtol()
  util/cutils: Rename qemu_strtoll(), qemu_strtoull()
  util/cutils: Rewrite documentation of qemu_strtol() & friends
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>