i386 code label alignment patch (version 2)

[John Wehle]

> Ian has raised an excellent point.  I think we're better off with
> a feature test.

Okay, I'll take a look at revising the patch.  Two issues:

  1) Ian suggested only picking up the version number from
     ../gas/configure.in when doing a Canadian Cross.  I'm not
     sure how to support a single tree native or cross build
     without checking for VERSION in ../gas since the assembler
     which will be used with gcc may not yet exist.
     My current logic is:

       a) If there is an executable assembler in the current
          directory, then check it.

       b) Check for VERSION in ../gas.

       c) If host == target then check the assembler in $path.

     Should I just drop "b" and not worry about single tree build /
     how would you like a single tree build to be handled?

  2) How should the results of the feature test(s) be expressed.
     I can think of two choices:

       a) Use the feature test to determine the minimum GAS version.
          If .p2align,,7 assembles then set GAS version to 2.8.

       b) Use a separate define for each feature.  If .p2align,,7
          assembles then define HAVE_GAS_MAX_SKIP_P2ALIGN.  If .p2align
          assembles then define HAVE_GAS_P2ALIGN.

     My only concern with "b" is that I can imagine an explosion of
     HAVE_GAS_xxx macros as new features of gas are used.  In general
     newer versions of gas will probably support the older features
     so it may be undesirable to have a lot of different defines where
     one version define will suffice.  The advantage of "b" is that it's
     finer grain and will handle the gas of a newer gas dropping an old
     feature.

-- John
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