[JVMCI] crash when materializing boxed values under -Xcomp

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# A fatal error has been detected by the Java Runtime Environment:
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# Internal Error (deoptimization.cpp:798), pid=26877, tid=8195
# guarantee(ik->is_initialized()) failed: java/lang/Character$CharacterCache must be initialized
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The above crash can happen when JVMCI compiled code escape analyzes a boxed char and needs to materialize it when deoptimizing the compiled code. The problem occurs when the caching class (java/lang/Character$CharacterCache in this case) has not been initialized. In normal execution where code is first interpreted and then compiled, this should never happen as the class will be initialized during interpretation. However, with `-XX:-TieredCompilation -Xcomp` it's possible for class initialization to not be interpreted meaning that it has to be done before the compiled code is executed.