Skip sys.prefix paths when cross-compiling

Patch setup.py to avoid adding sys.prefix lib/include directories unconditionally. The sys.prefix paths are now only added when platform guessing is enabled (prevents picking up host headers when cross-compiling). Also includes small comment and whitespace cleanups around environment path handling.

Author: FeodorFitsner

recipes/pillow/patches/setup-11.x.patch

@@ -1,5 +1,4 @@
 diff --git a/setup.py b/setup.py
-index a85731d..fbbb5b6 100644
 --- a/setup.py
 +++ b/setup.py
 @@ -355,9 +355,7 @@ class pil_build_ext(build_ext):
@@ -13,13 +12,13 @@ index a85731d..fbbb5b6 100644
          self.add_imaging_libs = ""
          build_ext.initialize_options(self)
          for x in self.feature:
-@@ -548,8 +546,10 @@ class pil_build_ext(build_ext):
-             for d in os.environ[k].split(os.path.pathsep):
+@@ -550,8 +548,10 @@ class pil_build_ext(build_ext):
+                 for d in os.environ[k].split(os.path.pathsep):
                      _add_directory(library_dirs, d)
 
 -        _add_directory(library_dirs, os.path.join(sys.prefix, "lib"))
 -        _add_directory(include_dirs, os.path.join(sys.prefix, "include"))
-+        # Skip adding sys.prefix paths when cross-compiling to avoid host headers
++        # Skip sys.prefix paths when cross-compiling to avoid host headers
 +        if not self.disable_platform_guessing:
 +            _add_directory(library_dirs, os.path.join(sys.prefix, "lib"))
 +            _add_directory(include_dirs, os.path.join(sys.prefix, "include"))