[Bug jit/63854] Fix memory leaks seen in JIT

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63854
Bug 63854 depends on bug 64003, which changed state.

Bug 64003 Summary: valgrind complains about get_attr_length_nobnd in 
insn-attrtab.c from i386.md
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64003

           What    |Removed                     |Added
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             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |---