Add ftmm.c to FreeType build.

Add ftmm.c to FreeType build.

The FreeType configuration is already building with
TT_CONFIG_OPTION_GX_VAR_SUPPORT, but the functions cannot be accessed
without base/ftmm.c. The ftmm.c file is small and simply exposes the
means to call the service which already exists on the ft_face.

patch from issue 1165563005 at patchset 1 (http://crrev.com/1165563005#ps1)

Committed: d1028db70bea988d1022e4d463de66581c696160

[Xianzhu, 2015-06-01 15:56:34]

Committed patchset #1 (id:1) manually as
d1028db70bea988d1022e4d463de66581c696160 (presubmit successful).