lib/unictype/bitmap.h, different signs of integers; with clang and groff

[Bjarni Ingi Gislason]

  CC       lib/uniwidth/libgnu_a-width.o
In file included from ../lib/uniwidth/width.c:51:
../lib/unictype/bitmap.h:31:14: warning: comparison of integers of
different signs: 'unsigned int' and 'const int' [-Wsign-compare]
  if (index1 < ((const int *) table)[0])
      ~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.