Require OSX >= 10.6.  Remove PowerPC unexec code.

* configure.ac: Require OSX 10.6.  Remove NSInteger test,
use nsfont for Gnustep, macfont for OSX.

* etc/NEWS: OSX required is 10.6 or newer.

* src/Makefile.in: Replace nsfont.o macfont.o with ns_fontfile in
comment.

* src/macfont.h (MAC_FONT_FORMAT_ATTRIBUTE, MAC_FONT_FORMAT_BITMAP)
(mac_font_copy_non_synthetic_table): Remove versions for OSX < 10.6

* src/nsfns.m: Always include src/macfont.h on COCOA.
(ns_filename_from_panel, ns_directory_from_panel)
(Fx_create_frame, Fns_popup_font_panel, ns_run_file_dialog)
(Fns_read_file_name, Fns_list_services): Remove code for OSX < 10.6

* src/nsterm.m: Always include src/macfont.h on COCOA.
(ns_update_auto_hide_menu_bar, ns_draw_fringe_bitmap)
(ns_dumpglyphs_image, ns_check_menu_open)
(applicationDidFinishLaunching)
(antialiasThresholdDidChange:)
(keyDown:, toggleFullScreen:, setPosition:portion:whole:): Remove
checks for OSX <= 10.5/10.6.
(changeFont:): Use macfont on COCOA, nsfont on GNUSTEP.
(syms_of_nsterm): Call syms_of_macfont on COCOA, syms_of_nsfont on
GNUSTEP.

* src/macfont.m: Remove >= 1050 check.
(macfont_create_family_with_symbol)
(macfont_get_glyph_for_character)
(mac_font_get_glyphs_for_variants)
(mac_ctfont_create_available_families, syms_of_macfont): Remove
code for OSX < 10.6.
(mac_font_family_group, mac_font_family_compare): Remove, only used
for OSX < 10.6.

* src/nsimage.m (allocInitFromFile:): Remove code for OSX < 10.6.

* src/nsmenu.m (NSMenuDidBeginTrackingNotification): Remove.
(x_activate_menubar, trackingNotification:): Remove check for
OSX >= 10.5.
(menuNeedsUpdate:): Remove check for OSX < 10.5.

* src/nsterm.h (MAC_OS_X_VERSION_10_4, MAC_OS_X_VERSION_10_5): Remove.
(NS_HAVE_NSINTEGER): Remove block.
Remove >= OSX 10.6 tests.

* src/unexmacosx.c: Remove include ppc/reloc.h.
(unrelocate, copy_dysymtab): Remove PPC code.
(rebase_reloc_address): Remove, only used for PPC: