Update dedicated.mk

remove the need for libPNG in dedicated server build

src/Makefile.d/dedicated.mk

-makedir:=$(makedir)/Dedicated
-
-sources+=$(call List,dedicated/Sourcefile)
-
-opts+=-DDEDICATED
-
-ifdef FREEBSD
-# on FreeBSD, we have to link to libpthread explicitly
-libs+=-lpthread
-endif
-
-ifdef MINGW
-libs+=-mconsole
-endif
-
-ifndef NOTHREADS
-opts+=-DHAVE_THREADS
-sources+=dedicated/i_threads.c
-endif
-
-NOOPENMPT=1
-NOGME=1
-NOHW=1
-NOUPNP=1
+makedir:=$(makedir)/Dedicated
+
+sources+=$(call List,dedicated/Sourcefile)
+
+opts+=-DDEDICATED
+
+ifdef FREEBSD
+# on FreeBSD, we have to link to libpthread explicitly
+libs+=-lpthread
+endif
+
+ifdef MINGW
+libs+=-mconsole
+endif
+
+ifndef NOTHREADS
+opts+=-DHAVE_THREADS
+sources+=dedicated/i_threads.c
+endif
+
+NOOPENMPT=1
+NOGME=1
+NOHW=1
+NOUPNP=1
+NOPNG=1