SPRINGFIELD — Signing a bill to decriminalize small amounts of marijuana would be, some legislators say, “low-hanging fruit” for Gov. Bruce Rauner, who is pushing for prison sentencing reform.The legislation passed the Illinois House and Senate last month with some Republican support, though 50 GOP lawmakers opposed the bill, which they said would increase the acceptance of the drug and send the wrong message to children.So far, the Republican governor has been mum on whether he will sign the bill, though …