menuselect: Remove ineffective weak attribute detection.

menuselect detects compiler support for multiple styles of weak
functions.  This is a remnant from 2013 when OPTIONAL_API required weak
functions.  It is no longer correct for menuselect to switch
dependencies from optional to required based on lack of weak function
support.

Note an issue remains - dependencies should switch from optional to
required based on OPTIONAL_API being enabled or disabled.  I don't think
this is possible.  menuselect needs to know at startup if OPTIONAL_API
is enabled or disabled, so the only way to fix this is to remove
OPTIONAL_API from menuselect and create a configure option.  I've left
the code that switches in place but it's preprocessed out.

Additionally removed:
- WEAKREF variable from Asterisk makeopts.in.
- Related disabled code from test_utils.
- Pointless AC_REVISION call from menuselect/configure.ac.

Change-Id: Ifa702e5f98eb45f338b2f131a93354632a8fb389

menuselect/configure.ac

@@ -15,7 +15,6 @@ AC_CONFIG_SRCDIR([menuselect.c])
 AC_CONFIG_HEADER(autoconfig.h)
 
 AC_COPYRIGHT("Menuselect")
-AC_REVISION($Revision$)
 
 AC_CANONICAL_BUILD
 AC_CANONICAL_HOST
@@ -81,37 +80,6 @@ AC_ARG_ENABLE([debug],
     esac])
 AC_SUBST(MENUSELECT_DEBUG)
 
-# Support weak symbols on a platform specific basis.  The Mac OS X
-# (Darwin) support must be isolated from the other platforms because
-# it has caused other platforms to fail.
-#
-case "${OSARCH}" in
-	darwin*)
-	# Allow weak symbol support on Darwin platforms only because there
-	# is active community support for it.
-	# However, Darwin seems to break weak symbols for each new version.
-	#
-	AST_GCC_ATTRIBUTE(weak_import, [], [], PBX_WEAKREF)
-
-	# Several other platforms including Linux have GCC versions that
-	# define the weak attribute.  However, this attribute is only
-	# setup for use in the code by Darwin.
-	AST_GCC_ATTRIBUTE(weak, [], [], PBX_WEAKREF)
-	;;
-	linux-gnu)
-	# Primarily support weak symbols on Linux platforms.
-	#
-	AST_GCC_ATTRIBUTE(weakref, [weakref("foo")], static, PBX_WEAKREF)
-	;;
-	*)
-	# Allow weak symbols on other platforms.  However, any problems
-	# with this feature on other platforms must be fixed by the
-	# community.
-	#
-	AST_GCC_ATTRIBUTE(weakref, [weakref("foo")], static, PBX_WEAKREF)
-	;;
-esac
-
 AC_FUNC_ALLOCA
 AC_CHECK_FUNCS([asprintf getloadavg setenv strcasestr strndup strnlen strsep unsetenv vasprintf])