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.
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