Windows installer pulls version from interpreter.

This should make version updates simpler. Also
try an make installer write to ProgramFiles instead
of ProgramFiles (x86) for 64 bit build.

build_win.bat

@@ -157,7 +157,11 @@ copy auxbin\jpm dist\jpm
 copy tools\jpm.bat dist\jpm.bat
 
 @rem Create installer
-"C:\Program Files (x86)\NSIS\makensis.exe" janet-installer.nsi
+janet.exe -e "(print janet/version)" > build\version.txt
+janet.exe -e "(print (= (os/arch) :x64))" > build\64bit.txt
+set /p JANET_VERSION= < build\version.txt
+set /p SIXTYFOUR= < build\64bit.txt
+"C:\Program Files (x86)\NSIS\makensis.exe" janet-installer.nsi /DVERSION=%JANET_VERSION% /DSIXTYFOUR=%SIXTYFOUR%
 exit /b 0
 
 @rem Run the installer. (Installs to the local user with default settings)

janet-installer.nsi

@@ -1,5 +1,4 @@
 # Version
-!define VERSION "1.6.0"
 !define PRODUCT_VERSION "${VERSION}.0"
 VIProductVersion "${PRODUCT_VERSION}"
 VIFileVersion "${PRODUCT_VERSION}"
@@ -14,8 +13,9 @@ VIFileVersion "${PRODUCT_VERSION}"
 !define MULTIUSER_INSTALLMODE_INSTDIR_REGISTRY_VALUENAME ""
 !define MULTIUSER_INSTALLMODE_INSTDIR "Janet-${VERSION}"
 
-# For now, use 32 bit folder as build is 32 bit
-# !define MULTIUSER_USE_PROGRAMFILES64
+!if ${SIXTYFOUR} == "true"
+    !define MULTIUSER_USE_PROGRAMFILES64
+!endif
 
 # Includes
 !include "MultiUser.nsh"

src/core/os.c

@@ -110,7 +110,7 @@ static Janet os_arch(int32_t argc, Janet *argv) {
 #elif defined(__EMSCRIPTEN__)
     return janet_ckeywordv("wasm");
 #elif (defined(__x86_64__) || defined(_M_X64))
-    return janet_ckeywordv("x86-64");
+    return janet_ckeywordv("x64");
 #elif defined(__i386) || defined(_M_IX86)
     return janet_ckeywordv("x86");
 #elif defined(_M_ARM64) || defined(__aarch64__)