Add support for PBXBuildStyle

[Bigpet]

Context 🕵️‍♀️

I was trying to use Xcodegen to reference a target inside a xcode project generated by cmake.

/* Begin PBXBuildStyle section */
		C3A1C34E5D9A41E99812FB9C /* Release */ = {
			isa = PBXBuildStyle;
			buildSettings = {
				COPY_PHASE_STRIP = NO;
			};
			name = Release;
		};
/* End PBXBuildStyle section */

Later on used in

/* Begin PBXProject section */
		5F89BF4899BD4F768A3616BC /* Project object */ = {
			isa = PBXProject;
			attributes = {
				BuildIndependentTargetsInParallel = YES;
				LastUpgradeCheck = 1340;
			};
			buildConfigurationList = A855B1006B43451EBA296B88 /* Build configuration list for PBXProject "myproj" */;
			buildSettings = {
			};
			buildStyles = (
				C3A1C34E5D9A41E99812FB9C /* Release */,
			);

What 🌱

It could not add a target from the cmake generated xcodeproj as a dependency and just returned the error "The element PBXBuildStyle is not supported."

Proposal 🎉

This element seems like it's the base of XCConfigurationList which is supported, so this element might be able to be handled similarly.

[Bigpet]

this seems related: CocoaPods/CocoaPods#6325

And they appear to mostly blame cmake as the culprit.

In case anyone lands here via google, I used this script from here before the initial generation to make it work. If CMake overwrites it again, it still works until you try to use xcodegen again: https://gist.github.com/Bigpet/9c8f950aa5dd3ad99923d4d98cf87209

[Bigpet]

I got my issue solved by editing the *.xcodeproj file. While I can't find any Reference to the element being "deprecated" or "outdated" officially. Apparently it's just accepted that if the XCode UI of newer versions doesn't generate an element, it's de-facto "outdated".