syslinux: remove outdated patch.

srcpkgs/syslinux/patches/syslinux-dont-build-dos-windows-targets.patch

@@ -1,12 +0,0 @@
-diff -Nur syslinux-4.02.orig//Makefile syslinux-4.02//Makefile
---- Makefile	2010-07-21 21:33:13.000000000 +0200
-+++ Makefile	2010-07-22 11:14:03.325522937 +0200
-@@ -55,7 +55,7 @@
- # files that depend only on the B phase, but may have to be regenerated
- # for "make installer".
- BSUBDIRS = codepage com32 lzo core memdisk modules mbr memdump gpxe sample \
--	   diag libinstaller dos win32 win64 dosutil
-+	   libinstaller
- ITARGET  =
- IOBJECTS = $(ITARGET) \
- 	utils/gethostip utils/isohybrid utils/mkdiskimage \