In ConstantUtils.skipOverFieldSignature, the current index instead of 0 is incorrectly returned if an invalid V is encountered.

https://github.com/openjdk/jdk/blob/5726d31e56530bbe7dee61ae04b126e20cb3611d/src/java.base/share/classes/java/lang/constant/ConstantUtils.java#L196

This issue doesn't directly permit creation of malformed ClassDesc or MethodTypeDesc, but it leads to ambiguous exceptions on certain inputs:

jshell> java.lang.constant.MethodTypeDesc.ofDescriptor("(IIIIIIII[[[[V)V")