net/asterisk1[68]: Remove obsolete patches

These patches are already included upstream. No functional change.

Reported by:	Naveen Albert <asterisk at phreaknet.org> (via email)

net/asterisk16/files/patch-main_asterisk.exports.in

---- main/asterisk.exports.in.orig	2020-07-09 15:39:17 UTC
-+++ main/asterisk.exports.in
-@@ -65,6 +65,8 @@
- 
- 		*/
- 		LINKER_SYMBOL_PREFIX_IO_stdin_used;
-+		LINKER_SYMBOL_PREFIX__progname;
-+		LINKER_SYMBOL_PREFIXenviron;
- 	local:
- 		*;
- };

net/asterisk18/files/patch-main_asterisk.exports.in

---- main/asterisk.exports.in.orig	2020-07-09 15:39:17 UTC
-+++ main/asterisk.exports.in
-@@ -65,6 +65,8 @@
- 
- 		*/
- 		LINKER_SYMBOL_PREFIX_IO_stdin_used;
-+		LINKER_SYMBOL_PREFIX__progname;
-+		LINKER_SYMBOL_PREFIXenviron;
- 	local:
- 		*;
- };