Log Message:
leptonica: updated to 1.75.2

1.75.2:
Converted several progs to standard regression tests.
Added these tests to the alltests_reg suite:
 adaptnorm_reg, binmorph1_reg, binmorph3_reg, equal_reg,
 extrema_reg, grayfill_reg, falsecolor_reg, grayquant_reg.
Autotools fix for restricting giflib to 5.1+, and allowing openjpeg 2.3