Fixes missing EOF newline warnings in a couple header files.

Fixes a few lint warnings which we received when building libsass:

    37) [0.166s] third_party/c/github.com/sass/sassc/bin: clang -Wall -pedantic -O3 ../sassc.c ../../libsass/lib/libsass.a -lstdc++ -lm -stdlib=libc++ -I../../libsass -o sassc
    In file included from ../sassc.c:5:
    In file included from ../../libsass/sass_interface.h:6:
    In file included from ../../libsass/sass.h:6:
    ../../libsass/sass_values.h:113:7: warning: no newline at end of file [-Wnewline-eof]
    #endif
          ^
    In file included from ../sassc.c:5:
    In file included from ../../libsass/sass_interface.h:6:
    ../../libsass/sass.h:31:7: warning: no newline at end of file [-Wnewline-eof]
    #endif
          ^
    2 warnings generated.
    [    ETA=<1s Remaining=0  Active=0    ] 100%