Add missing Unicode/MBCS defines to MSC command line

Note that the defines are showing up in CFLAGS rather than DEFINES. The tool adapter API needs to be modified before they can be placed in the defines list where they should be.

src/_premake_init.lua

@@ -1364,6 +1364,7 @@
 --
 -----------------------------------------------------------------------------
 
+	characterset "Default"
 	clr "Off"
 	editorintegration "Off"
 	exceptionhandling "Default"

src/tools/msc.lua

@@ -29,6 +29,11 @@
 --
 
 	msc.cflags = {
+		characterset = {
+			Default = { '/D"_UNICODE"', '/D"UNICODE"' },
+			MBCS = '/D"_MBCS"',
+			Unicode = { '/D"_UNICODE"', '/D"UNICODE"' },
+		},
 		clr = {
 			On = "/clr",
 			Unsafe = "/clr",

tests/tools/test_msc.lua

@@ -311,6 +311,28 @@
 	end
 
 
+--
+-- Check handling of character set switches
+--
+
+	function suite.cflags_onCharSetDefault()
+		prepare()
+		test.contains('/D"_UNICODE"', msc.getcflags(cfg))
+	end
+
+	function suite.cflags_onCharSetUnicode()
+		characterset "Unicode"
+		prepare()
+		test.contains('/D"_UNICODE"', msc.getcflags(cfg))
+	end
+
+	function suite.cflags_onCharSetMBCS()
+		characterset "MBCS"
+		prepare()
+		test.contains('/D"_MBCS"', msc.getcflags(cfg))
+	end
+
+
 --
 -- Check handling of system search paths.
 --
@@ -342,3 +364,4 @@
 		prepare()
 		test.contains('/NODEFAULTLIB:lib1.lib', msc.getldflags(cfg))
 	end
+