RFR: 8353632: [Linux] Undefined reference to PlatformSupport::OBSERVED_SETTINGS with C++14

[Kevin Rushforth]

Fixes a link error that occurs when using C++14 to compile and link JavaFX on Linux.


in function `PlatformSupport::PlatformSupport(JNIEnv_*, _jobject*)':
PlatformSupport.cpp:90: undefined reference to `PlatformSupport::OBSERVED_SETTINGS'


The solution, proposed by @johanvos, is to define `PlatformSupport::OBSERVED_SETTINGS` in `PlatformSupport.cpp`.

I have tested this using gcc 13.2 and 14.2 using C++17 and it builds and runs as expected. Johan has already tested a variant of this on C++14, but I will wait for his explicit review.

-------------

Commit messages:
 - 8353632: [Linux] Undefined reference to PlatformSupport::OBSERVED_SETTINGS with C++14

Changes: https://git.openjdk.org/jfx/pull/1768/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1768&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8353632
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1768.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1768/head:pull/1768

PR: https://git.openjdk.org/jfx/pull/1768