Unify copies of WebKitTargetConditionals.xcconfig. These files had already started to diverge: ``` $ find Source -name WebKitTargetConditionals.xcconfig -exec cksum {} \; 3779096934 8290 Source/WebKit/Configurations/WebKitTargetConditionals.xcconfig 2307507470 8458 Source/JavaScriptCore/Configurations/WebKitTargetConditionals.xcconfig 3779096934 8290 Source/WebKitLegacy/mac/Configurations/WebKitTargetConditionals.xcconfig 1280648406 8463 Source/WebGPU/Configurations/WebKitTargetConditionals.xcconfig 3874766778 6789 Source/WebInspectorUI/Configurations/WebKitTargetConditionals.xcconfig 3779096934 8290 Source/WebCore/Configurations/WebKitTargetConditionals.xcconfig 3779096934 8290 Source/WebCore/PAL/Configurations/WebKitTargetConditionals.xcconfig 1713230325 8290 Source/ThirdParty/ANGLE/Configurations/WebKitTargetConditionals.xcconfig 3779096934 8290 Source/ThirdParty/libwebrtc/Configurations/WebKitTargetConditionals.xcconfig ```
<rdar://problem/99233826>
Pull request: https://github.com/WebKit/WebKit/pull/3742
Committed 253873@main (3f8075f50078): <https://commits.webkit.org/253873@main> Reviewed commits have been landed. Closing PR #3742 and removing active labels.