[CMAKE] Make vc6 build process easier

Added environment variable initialization to CMakePresets for vc6

It will no longer be necessary to setup a separate CMD session
with vsvars32.bat just for VC6 builds.

Switching to and from a vc6 build should now just be a matter of
switching presets

Author: aliendroid1

CMakePresets.json

@@ -25,6 +25,16 @@
                 }
             }
         },
+        {
+            "name": "vc6-vars",
+            "hidden": true,
+            "environment": {
+                "VS6_DIR": "$env{ProgramFiles(x86)}\\Microsoft Visual Studio",
+                "PATH": "$env{VS6_DIR}\\VC98\\BIN;$env{VS6_DIR}\\Common\\Tools;$env{VS6_DIR}\\Common\\Tools\\WinNT;$env{VS6_DIR}\\Common\\MSDev98\\Bin;penv{PATH}",
+                "INCLUDE": "$env{VS6_DIR}\\VC98\\INCLUDE;$env{VS6_DIR}\\VC98\\MFC\\INCLUDE;$env{VS6_DIR}\\VC98\\ATL\\INCLUDE;penv{INCLUDE}",
+                "LIB":  "$env{VS6_DIR}\\VC98\\LIB;$env{VS6_DIR}\\VC98\\MFC\\LIB;$penv{LIB}"
+            }
+        },
         {
             "name": "vc6-profile",
             "displayName": "Windows 32bit VC6 Profile",
@@ -52,6 +62,14 @@
                 "RTS_BUILD_OPTION_DEBUG": "ON"
             }
         },
+        {
+            "name": "vc6-easy",
+            "inherits": ["vc6","vc6-vars"]
+        },
+        {
+            "name": "vc6-debug-easy",
+            "inherits": ["vc6-debug","vc6-vars"]
+        },
         {
             "name": "default",
             "displayName": "Default Config (don't use directly!)",
@@ -168,7 +186,7 @@
             "displayName": "Unix 32bit VCPKG Release"
         }
     ],
-    "buildPresets": [
+    "buildPresets": [      
         {
             "name": "vc6",
             "configurePreset": "vc6",