Clean up podspec: drop redundant libxml2 flag and requires_arc

- Remove `-I$(SDKROOT)/usr/include/libxml2` from the WebDAV subspec: the
  modern SDK ships a libxml2 module map that resolves <libxml/parser.h>
  with no extra header search path (verified via pod lib lint).
- Remove all `requires_arc = true` declarations: ARC is the CocoaPods
  default and the sources already enforce it with #error guards. They
  were leftovers from when GCDWebServer <= 3.1 supported MRC.
- Remove the leftover pod trunk template comment block.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

GCDWebServer.podspec

@@ -1,10 +1,3 @@
-# http://guides.cocoapods.org/syntax/podspec.html
-# http://guides.cocoapods.org/making/getting-setup-with-trunk.html
-# $ sudo gem update cocoapods
-# (optional) $ pod trunk register {email} {name} --description={computer}
-# $ pod trunk --verbose push
-# DELETE THIS SECTION BEFORE PROCEEDING!
-
 Pod::Spec.new do |s|
   s.name     = 'GCDWebServer'
   s.version  = '3.5.4'
@@ -17,14 +10,12 @@ Pod::Spec.new do |s|
   s.ios.deployment_target = '16.0'
   s.tvos.deployment_target = '16.0'
   s.osx.deployment_target = '12.0'
-  s.requires_arc = true
-  
+
   s.default_subspec = 'Core'
   
   s.subspec 'Core' do |cs|
     cs.source_files = 'GCDWebServer/**/*.{h,m}'
     cs.private_header_files = "GCDWebServer/Core/GCDWebServerPrivate.h"
-    cs.requires_arc = true
     cs.ios.library = 'z'
     cs.ios.frameworks = 'CoreServices', 'CFNetwork'
     cs.tvos.library = 'z'
@@ -36,17 +27,14 @@ Pod::Spec.new do |s|
   s.subspec 'WebDAV' do |cs|
     cs.dependency 'GCDWebServer/Core'
     cs.source_files = 'GCDWebDAVServer/*.{h,m}'
-    cs.requires_arc = true
     cs.ios.library = 'xml2'
     cs.tvos.library = 'xml2'
     cs.osx.library = 'xml2'
-    cs.compiler_flags = '-I$(SDKROOT)/usr/include/libxml2'
   end
   
   s.subspec 'WebUploader' do |cs|
     cs.dependency 'GCDWebServer/Core'
     cs.source_files = 'GCDWebUploader/*.{h,m}'
-    cs.requires_arc = true
     cs.resource = "GCDWebUploader/GCDWebUploader.bundle"
   end 
 end