UnixPkg: Fix build for Linux

UnixPkg/UnixSnpDxe is currently BSD/OS X specific.
Therefore we only build it if "-D NETWORK_SUPPORT"
is used on the build command line.

UnixPkg/build.sh and UnixPkg/build64.sh are updated to
automatically define NETWORK_SUPPORT if building on OS X.

<net/if_dl.h> and <net/bpf.h> are also only included in
UnixPkg/Include/Common/UnixInclude.h if __APPLE__ is defined.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11346 6f19259b-4bc3-4df7-8a09-765794883524

UnixPkg/build.sh

@@ -41,6 +41,7 @@ fi
 # Pick a default tool type for a given OS
 #
 TARGET_TOOLS=MYTOOLS
+NETWORK_SUPPORT=
 case `uname` in
   CYGWIN*) echo Cygwin not fully supported yet. ;;
   Darwin*)
@@ -52,6 +53,7 @@ case `uname` in
       else
         TARGET_TOOLS=XCODE32
       fi
+      NETWORK_SUPPORT="-D NETWORK_SUPPORT"
       ;;
   Linux*) TARGET_TOOLS=ELFGCC ;;
 
@@ -115,6 +117,6 @@ done
 #
 echo $PATH
 echo `which build`
-build -p $WORKSPACE/UnixPkg/UnixPkg.dsc         -a IA32 -t $TARGET_TOOLS -n 3 $1 $2 $3 $4 $5 $6 $7 $8
+build -p $WORKSPACE/UnixPkg/UnixPkg.dsc         -a IA32 -t $TARGET_TOOLS $NETWORK_SUPPORT -n 3 $1 $2 $3 $4 $5 $6 $7 $8
 exit $?