Fix mac compilation

Update mac configure code with FFmpeg current, this avoids the linker warning:
ld: warning: -read_only_relocs cannot be used with x86_64
Now use -read_only_relocs flag only on 32-bit x86

Also fix compiling on Tiger which would get '-dylib_compatibility_version must be greater than zero' error.

mythtv/configure

@@ -3127,18 +3127,18 @@ case $target_os in
         strip="strip -d"
         ;;
     darwin)
-        _restrict=__restrict__
-        enable malloc_aligned
-        gas="gas-preprocessor.pl $cc"
-        enabled ppc && add_asflags -force_cpusubtype_ALL
-        # Workaround compile errors from missing u_int/uint def
-        CPPFLAGS=`echo $CPPFLAGS | sed 's/-D_POSIX_C_SOURCE=200112//'`
-        # Workaround compile errors from missing ru_maxrss
-        add_cppflags -D_DARWIN_C_SOURCE
         enable  appleremote
         enable  backend
         enable  darwin
         disable dvb
+        disable v4l1
+        disable v4l2
+        disable x11
+        # Workaround compile errors from missing u_int/uint def
+        CFLAGS=`echo $CFLAGS | sed 's/-D_POSIX_C_SOURCE=200112//'`
+        CPPFLAGS=`echo $CPPFLAGS | sed 's/-D_POSIX_C_SOURCE=200112//'`
+        # Workaround compile errors from missing ru_maxrss
+        add_cppflags -D_DARWIN_C_SOURCE
         # Prevent linker problems on default Intel 10.5 XCode:
         ldver=$(ld -v 2>&1 | sed -e s/^[^-]*-//)
         osxver=$(uname -r | cut -c 1)
@@ -3151,13 +3151,19 @@ EOF
             disable mmx
             enable disable_mmx_for_debugging   # prevent later call to die
         fi
-        disable v4l1
-        disable v4l2
-        disable x11
-        # Workaround compile errors from missing gmtime_r/localtime_r/uint def
-        CFLAGS=`echo $CFLAGS | sed 's/-D_POSIX_C_SOURCE=200112//'`
+
         ###### Standard ffmpeg configure stuff follows:
-        SHFLAGS='-dynamiclib -Wl,-single_module -Wl,-install_name,$(SHLIBDIR)/$(SLIBNAME),-current_version,$(LIBVERSION),-compatibility_version,$(LIBMAJOR) -Wl,-read_only_relocs,suppress'
+        enable malloc_aligned
+        gas="gas-preprocessor.pl $cc"
+        enabled ppc && add_asflags -force_cpusubtype_ALL
+
+        build_os_ver=$(uname -r)
+        if test ${build_os_ver:0:1} = 8; then
+            SHFLAGS='-dynamiclib -Wl,-single_module -Wl,-install_name,$(SHLIBDIR)/$(SLIBNAME),-current_version,$(LIBVERSION)'
+        else
+            SHFLAGS='-dynamiclib -Wl,-single_module -Wl,-install_name,$(SHLIBDIR)/$(SLIBNAME),-current_version,$(LIBVERSION),-compatibility_version,$(LIBMAJOR)'
+        fi
+        enabled x86_32 && append SHFLAGS -Wl,-read_only_relocs,suppress
         strip="${strip} -x"
         add_ldflags -Wl,-dynamic,-search_paths_first
         SLIBSUF=".dylib"