RFR: 8278472: Invalid value set to CANDIDATEFORM structure

[Alexey Ivanov]

According to the Windows API reference, `dwStyle` of [`CANDIDATEFORM`](https://docs.microsoft.com/en-us/windows/win32/api/imm/ns-imm-candidateform) structure should be set to `CFS_CANDIDATEPOS` or `CFS_EXCLUDE`. So, `CFS_POINT` is wrong here.

There are two instances in `AwtComponent::SetCandidateWindow` in [`awt_Component.cpp`](https://github.com/openjdk/jdk/blob/f90425a1cbbc686045c87086af586e62f05f6c49/src/java.desktop/windows/native/libawt/windows/awt_Component.cpp#L3914) where the incorrect value is used.

Initially, I created this PR for jdk18. [It was suggested](https://github.com/openjdk/jdk18/pull/54#issuecomment-1006432326) to place this fix into the mainline, so this a continuation to [jdk18/pull/54](https://github.com/openjdk/jdk18/pull/54).

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Commit messages:
 - 8278472: Invalid value set to CANDIDATEFORM structure

Changes: https://git.openjdk.java.net/jdk/pull/7146/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7146&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278472
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7146.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7146/head:pull/7146

PR: https://git.openjdk.java.net/jdk/pull/7146