Determine an Objective C compiler to use. If
OBJC is not already
set in the environment, check for Objective C compilers. Set output
OBJC to the name of the compiler found.
This macro may, however, be invoked with an optional first argument
which, if specified, must be a blank-separated list of Objective C compilers to
search for. This just gives the user an opportunity to specify an
alternative search list for the Objective C compiler. For example, if you
didn't like the default order, then you could invoke
AC_PROG_OBJC([gcc objcc objc])
If using the GNU Objective C compiler, set shell variable
GOBJC to ‘yes’. If output variable
OBJCFLAGS was not
already set, set it to -g -O2 for the GNU Objective C
compiler (-O2 on systems where gcc does not accept
-g), or -g for other compilers.