do not autoprobe deps when we disabled them

--- a/converter/other/Makefile
+++ b/converter/other/Makefile
@@ -22,6 +22,7 @@
 # Also note that in both cases, the shell command fails if $(PKG_CONFIG)
 # doesn't even exist.
 
+ifneq ($(XML2_LIBS),NONE)
 TEST_PKGCONFIG_LIBXML2 := \
   if $(PKG_CONFIG) libxml-2.0 --exists; then echo exists; fi
 
@@ -38,6 +39,7 @@
     XML2_CFLAGS=$(shell xml2-config --cflags)
   endif
 endif
+endif
 
 SUBDIRS = jbig pnmtopalm jpeg2000 cameratopam pamtosvg
 ifneq ($(BUILD_FIASCO), N)
@@ -50,6 +52,7 @@
   endif
 endif
 
+ifneq ($(PNGLIB),NONE)
 TEST_PKGCONFIG_LIBPNG := \
   if $(PKG_CONFIG) libpng$(PNGVER) --exists; then echo exists; fi
 
@@ -75,6 +78,7 @@
     endif
   endif
 endif
+endif
 
 ifneq ($(JPEGLIB),NONE)
   ifneq ($(JPEGHDR_DIR)x,x)
--- a/other/pamx/Makefile
+++ b/other/pamx/Makefile
@@ -9,6 +9,7 @@
 
 EXTERN_INCLUDE =
 
+ifneq ($(X11LIB),NONE)
 TEST_PKGCONFIG_X11 := \
   if $(PKG_CONFIG) x11 --exists; then echo exists; fi
 
@@ -36,6 +37,7 @@
 	  window.o \
 
 endif
+endif
 
 BINARIES = $(PORTBINARIES)
 
@@ -49,12 +51,14 @@
 
 include $(SRCDIR)/common.mk
 
+ifneq ($(X11LIB),NONE)
 ifeq ($(shell $(TEST_PKGCONFIG_X11)),)
   # Pkg-config has never heard of X11, or doesn't even exist
   X11_LIBOPTS = $(shell $(LIBOPT) $(LIBOPTR) $(X11LIB))
 else
   X11_LIBOPTS = $(shell $(PKG_CONFIG) x11 --libs)
 endif
+endif
 
 pamx: image.o send.o window.o
 pamx: ADDL_OBJECTS = image.o send.o window.o