RFR: 8364087: Amend comment in globalDefinitions.hpp on "classfile_constants.h" include

[Francesco Andreuzzi]

The comment was introduced in [8231844](https://github.com/fandreuz/jdk/commit/fce43203699336e9513d06cd54b66735e93234a4). I looked around, and `<jvm.h>` is not included in any of the headers included by `globalDefinitions.hpp`, neither now nor in the original commit. Thus, I propose to amend the comment, as it [turned out to be confusing](https://github.com/openjdk/jdk/pull/26428/files#r2229575525) during an header clean up. 

Including `classfile_constants.h` is needed for e.g. `JVM_T_CHAR`, as stated by the comment, thus I'm going to leave that part intact.

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Commit messages:
 - amend comment

Changes: https://git.openjdk.org/jdk/pull/26573/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26573&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364087
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26573.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26573/head:pull/26573

PR: https://git.openjdk.org/jdk/pull/26573