[Pixman] mips* asm exports symbols that should not export

[YunQiang Su]

Hi, folks,

When build pixman with mips64r2 options, I get some addational symbols export,
while they were supposed not to be export.

More details can be found in:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=719059

The build log can be found from:
    http://mips64el.debian.net/attempted/pixman_0.30.2-2_mips64el.build.xz

-- 
YunQiang Su