Fix windows debug builds (obj file too large)

This fixes a "too many sections" issue
```
Fatal error: can't write 159 bytes to section .text of build/libs/ardour/luabindings.cc.1.o: 'file too big'
x86_64-w64-mingw32-as: build/libs/ardour/luabindings.cc.1.o: too many sections (36781)
```

libs/ardour/wscript

@@ -129,7 +129,6 @@ libardour_sources = [
         'ltc_file_reader.cc',
         'ltc_slave.cc',
         'lua_api.cc',
-        'luabindings.cc',
         'luaproc.cc',
         'luascripting.cc',
         'meter.cc',
@@ -461,6 +460,25 @@ def build(bld):
     if bld.is_defined('AUDIOUNIT_SUPPORT'):
         obj.source += [ 'audio_unit.cc', 'auv2_scan.cc' ]
 
+    lua_cxxflags = bld.env['compiler_flags_dict']['pic']
+    if bld.env['build_target'] == 'mingw' and bld.env['DEBUG']:
+        lua_cxxflags += " -Og -Wa,-mbig-obj"
+
+    bld(features = 'cxx cxxstlib asm',
+        source   = "luabindings.cc" ,
+        cxxflags = lua_cxxflags,
+        includes = obj.includes,
+        use      = ['libpbd','libmidipp','libevoral',
+                    'libtemporal',
+                    'liblua',
+                    'zita-resampler',
+                    'zita-convolver',
+                   ],
+        uselib   = obj.uselib,
+        target   = 'luabindings')
+
+    obj.use += ['luabindings' ]
+
     avx_sources = []
     fma_sources = []
     avx512f_sources = []

tools/x-win/compile.sh

@@ -63,17 +63,8 @@ export WINRC=${XPREFIX}-windres
 export RANLIB=${XPREFIX}-ranlib
 export DLLTOOL=${XPREFIX}-dlltool
 
-if grep -q optimize <<<"$ARDOURCFG"; then
-	OPT=""
-else
-	#debug-build luabindings.cc, has > 60k symbols.
-	# -Wa,-mbig-obj has an unreasonable long build-time
-	# -Og to the rescue.
-	OPT=" -Og"
-fi
-
-CFLAGS="-mstackrealign$OPT" \
-CXXFLAGS="-mstackrealign$OPT" \
+CFLAGS="-mstackrealign" \
+CXXFLAGS="-mstackrealign" \
 LDFLAGS="-L${PREFIX}/lib" \
 DEPSTACK_ROOT="$PREFIX" \
 ./waf configure \