PS4: Switch default build to amalgamated and LJ_GC64 mode.

Thanks to Eddie Edwards.

src/ps4build.bat

@@ -2,7 +2,19 @@
 @rem Donated to the public domain.
 @rem
 @rem Open a "Visual Studio .NET Command Prompt" (64 bit host compiler)
+@rem or "VS2015 x64 Native Tools Command Prompt".
+@rem
 @rem Then cd to this directory and run this script.
+@rem
+@rem Recommended invocation:
+@rem
+@rem ps4build        release build, amalgamated, 64-bit GC
+@rem ps4build debug    debug build, amalgamated, 64-bit GC
+@rem
+@rem Additional command-line options (not generally recommended):
+@rem
+@rem gc32 (before debug)    32-bit GC
+@rem noamalg (after debug)  non-amalgamated build
 
 @if not defined INCLUDE goto :FAIL
 @if not defined SCE_ORBIS_SDK_DIR goto :FAIL
@@ -15,6 +27,14 @@
 @set DASMDIR=..\dynasm
 @set DASM=%DASMDIR%\dynasm.lua
 @set ALL_LIB=lib_base.c lib_math.c lib_bit.c lib_string.c lib_table.c lib_io.c lib_os.c lib_package.c lib_debug.c lib_jit.c lib_ffi.c
+@set GC64=-DLUAJIT_ENABLE_GC64
+@set DASC=vm_x64.dasc
+
+@if "%1" neq "gc32" goto :NOGC32
+@shift
+@set GC64=
+@set DASC=vm_x86.dasc
+:NOGC32
 
 %LJCOMPILE% host\minilua.c
 @if errorlevel 1 goto :BAD
@@ -28,10 +48,10 @@ if exist minilua.exe.manifest^
 @if not errorlevel 8 goto :FAIL
 
 @set DASMFLAGS=-D P64 -D NO_UNWIND
-minilua %DASM% -LN %DASMFLAGS% -o host\buildvm_arch.h vm_x86.dasc
+minilua %DASM% -LN %DASMFLAGS% -o host\buildvm_arch.h %DASC%
 @if errorlevel 1 goto :BAD
 
-%LJCOMPILE% /I "." /I %DASMDIR% -DLUAJIT_TARGET=LUAJIT_ARCH_X64 -DLUAJIT_OS=LUAJIT_OS_OTHER -DLUAJIT_DISABLE_JIT -DLUAJIT_DISABLE_FFI -DLUAJIT_NO_UNWIND host\buildvm*.c
+%LJCOMPILE% /I "." /I %DASMDIR% %GC64% -DLUAJIT_TARGET=LUAJIT_ARCH_X64 -DLUAJIT_OS=LUAJIT_OS_OTHER -DLUAJIT_DISABLE_JIT -DLUAJIT_DISABLE_FFI -DLUAJIT_NO_UNWIND host\buildvm*.c
 @if errorlevel 1 goto :BAD
 %LJLINK% /out:buildvm.exe buildvm*.obj
 @if errorlevel 1 goto :BAD
@@ -54,7 +74,7 @@ buildvm -m folddef -o lj_folddef.h lj_opt_fold.c
 @if errorlevel 1 goto :BAD
 
 @rem ---- Cross compiler ----
-@set LJCOMPILE="%SCE_ORBIS_SDK_DIR%\host_tools\bin\orbis-clang" -c -Wall -DLUAJIT_DISABLE_FFI
+@set LJCOMPILE="%SCE_ORBIS_SDK_DIR%\host_tools\bin\orbis-clang" -c -Wall -DLUAJIT_DISABLE_FFI %GC64%
 @set LJLIB="%SCE_ORBIS_SDK_DIR%\host_tools\bin\orbis-ar" rcus
 @set INCLUDE=""
 
@@ -63,14 +83,14 @@ orbis-as -o lj_vm.o lj_vm.s
 @if "%1" neq "debug" goto :NODEBUG
 @shift
 @set LJCOMPILE=%LJCOMPILE% -g -O0
-@set TARGETLIB=libluajitD.a
+@set TARGETLIB=libluajitD_ps4.a
 goto :BUILD
 :NODEBUG
 @set LJCOMPILE=%LJCOMPILE% -O2
-@set TARGETLIB=libluajit.a
+@set TARGETLIB=libluajit_ps4.a
 :BUILD
 del %TARGETLIB%
-@if "%1"=="amalg" goto :AMALG
+@if "%1" neq "noamalg" goto :AMALG
 for %%f in (lj_*.c lib_*.c) do (
   %LJCOMPILE% %%f
   @if errorlevel 1 goto :BAD