Remove PHP_EXTENSION target property

This seems to be a redundant configuration on the long-run.

Author: petk

cmake/cmake/Extensions.cmake

@@ -31,7 +31,6 @@ https://bugs.php.net/53141
 
 Custom CMake properties:
 
-* PHP_EXTENSION
 * PHP_ZEND_EXTENSION
 * PHP_EXTENSION_<extension>_DEPS
 #]=============================================================================]
@@ -42,12 +41,6 @@ include_guard(GLOBAL)
 # CMake custom properties.
 ################################################################################
 
-define_property(
-  TARGET
-  PROPERTY PHP_EXTENSION
-  BRIEF_DOCS "Whether the target is a PHP extension"
-)
-
 define_property(
   TARGET
   PROPERTY PHP_ZEND_EXTENSION
@@ -404,9 +397,6 @@ function(php_extensions_postconfigure extension)
     add_library(PHP::ext::${extension} ALIAS php_ext_${extension})
   endif()
 
-  # Mark target as PHP extension.
-  set_property(TARGET php_ext_${extension} PROPERTY PHP_EXTENSION TRUE)
-
   # Set target output filename to "<extension>".
   get_target_property(output php_ext_${extension} OUTPUT_NAME)
   if(NOT output)