||Prints a "checking <message>" text during configure.
||Gives the result to AC_MSG_CHECKING; should specify either yes or no as value.
||Prints message as error message during configure and aborts the script.
||Adds #define to php_config.h with the value of value and a comment that says description (this is useful for conditional compilation of your module).
||Adds a compiler include path; for example, used if the module needs to add search paths for header files.
||Specifies an additional library to link.
||Quite a powerful macro, adding the module with description to the configure --help output. PHP checks whether the option --with-<modulename> is given to the configure script. If so, it runs the script unconditionaltest (for example, --with-myext=yes), in which case the value of the option is contained in the variable $withval. Otherwise, it executes conditionaltest.
||This macro is a must to call for PHP to configure your extension. You can supply a second argument in addition to your module name, indicating whether you intend compilation as a shared module. This will result in a definition at compile time for your source as COMPILE_DL_<modulename>.