[PATCH] Fixes tree-loop-distribute-patterns issues

[Roland McGrath]

> On x86_64 GLIBC 2.17 rtld-memset code use is 'sysdeps/x86_64/multiarch/memset.S'
> (and it won't generate a recursive call regarding the CFLAGS used), however on
> some point in 2.18 the build started to select 'sysdeps/x86_64/rtld-memset.c'
> instead.

Any rtld-foo source file will be chosen ahead of all foo source files.  So
if the sysdeps directory selection should affect whether a lower-priority
sysdeps subdirectory's rtld-foo is chosen over a higher-priority one's foo,
then the higher-priority one will need a rtld-foo that #include's foo.