Apply the fix for gcc PR #9812, which fixes generation of XFmode (long double)
code on m68k. In pure gcc tradition, even though the issue has been
acknowledged as a bug introduced around gcc 2.5, it was considered as
`not a regression' with subtle semantics tricks, and only fixed in 3.4.x
although the fix was available for a long time.

Although this changes an MI file, this chunk actually removes a no longer
used function which was only ever used on m68k.

Add support for position independent executables. This adds compile flags
-fpie & -fPIE which are similar to -fpic & -fPIC except that the resulting
objects can not be used in shared libraries due to an additional
optimization for pie. This also adds the -pie link flag which produces a
pie executable given pic or pie objects. Combining -pie with -static is
currently disabled. The only gcc3 arch that doesn't support pie at moment
is arm due to binutils relocation bugs.

ok kettenis@

Make gcc(1) really ignore __attribute__((visibility)) if HAVE_GAS_HIDDEN isn't
defined.

ok miod@

branches: 1.1.1;
Initial revision