EmulatorPkg: require GCC48 or later

We're about to remove BaseTools support for GCC44..GCC47. Reject those gcc
versions cleanly in "EmulatorPkg/build.sh", and drop build flags too that
are specific to them.

No GCC44..GCC47 references remain under EmulatorPkg after this patch.

Cc: Andrew Fish <afish@apple.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1377
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

EmulatorPkg/build.sh

@@ -48,7 +48,7 @@ PLATFORMFILE=
 LAST_ARG=
 RUN_EMULATOR=no
 CLEAN_TYPE=none
-TARGET_TOOLS=GCC44
+TARGET_TOOLS=GCC48
 NETWORK_SUPPORT=
 BUILD_NEW_SHELL=
 BUILD_FAT=
@@ -93,22 +93,10 @@ case `uname` in
 
     gcc_version=$(gcc -v 2>&1 | tail -1 | awk '{print $3}')
     case $gcc_version in
-      [1-3].*|4.[0-3].*)
-        echo EmulatorPkg requires GCC4.4 or later
+      [1-3].*|4.[0-7].*)
+        echo EmulatorPkg requires GCC4.8 or later
         exit 1
         ;;
-      4.4.*)
-        TARGET_TOOLS=GCC44
-        ;;
-      4.5.*)
-        TARGET_TOOLS=GCC45
-        ;;
-      4.6.*)
-        TARGET_TOOLS=GCC46
-        ;;
-      4.7.*)
-        TARGET_TOOLS=GCC47
-        ;;
       4.8.*)
         TARGET_TOOLS=GCC48
         ;;