Rule 10.1 : prohibit implict signed/unsigned conversions

These typically apply to initializations with bit patterns.

  ./src/alloc.c
  ./src/locale.c
  ./src/scanformat.c
  ./src/string.c
  ./src/sun_math/Double_precision/s_ceil.c
  ./src/sun_math/ansi_fp.c
  ./src/time.c
  ./src/wctype.c
  ./src/wmem.c
  ./src/wtime.c