CPU FLAGS X86 conversion

The basic idea is rather simple: replace CPU feature flags with matching flags from profiles/desc/cpu_flags_x86.desc. Few notes though:


 * 1) make sure not to accidentally change the option name, e.g. $(use_enable mmx) -> $(use_enable cpu_flags_x86_mmx mmx).
 * 2) The list of packages may be incomplete, esp. wrt packages that use custom local flag names. It may also contain extraneous packages, e.g. we need to check all uses of USE=aes.
 * 3) Some flags were renamed, e.g. aes-ni -> cpu_flags_x86_aes.
 * 4) Some flags are incorrect, e.g. sse4 doesn't exist. It's either sse4_1, sse4_2, see4a or some combination of the three.
 * 5) If you need extra flags, please bring it up for discussion first. Do not introduce more local flags, we have enough mess with them.
 * 6) Flags should be used when code (e.g. assembly) is compiled conditionally. When used only to control -mfoo options, the flags should be removed.

Packages
Here's my list of packages that still need to be converted. Please remove packages once you convert them.