X86: Get rid of "inline" on the MicroPanic constructor in decoder.cc.
X86: Get rid of "inline" on the MicroPanic constructor in decoder.cc.

This was making certain versions of gcc omit the function from the object file
which would break the build.

andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin