sg_zing_template.c: more signed/unsigned casts
sg_zing_template.c: more signed/unsigned casts

sg_zing_template.c: In function ‘SG_zingtemplate__validate__constraints__string’:
sg_zing_template.c:1017: error: comparison between signed and unsigned integer expressions
sg_zing_template.c:1067: error: comparison between signed and unsigned integer expressions
sg_zing_template.c:1076: error: comparison between signed and unsigned integer expressions

Signed-off-by: Ævar Arnfjörð Bjarmason <0135fcc047f75af264c800977a73e353c6ba842d@gmail.com>

avar/veracity,avar/veracity,avar/veracity