Fix installing uClibc headers for versions prior to 0.9.30.
Fix a comment about installing uClibc.
Automatically enable // build for uClibc versions that can be built in //.

-------- diffstat follows --------
/trunk/scripts/build/libc/uClibc.sh | 32 23 9 0 +++++++++++++++++++++++---------
/trunk/config/libc/uClibc.in | 12 7 5 0 +++++++-----
2 files changed, 30 insertions(+), 14 deletions(-)

 # x86_64 specific options

 config ARCH_x86_64

     select ARCH_64

     select ARCH_SUPPORT_ARCH

     select ARCH_SUPPORT_CPU

     select ARCH_SUPPORT_TUNE

     help

       The x86_64 architecture, as defined by:

         http://www.amd.com/us-en/Processors/DevelopWithAMD/0,,30_2252_875_7044,00.html