Display the build platform and architecture in the JitDump

src/jit/compiler.cpp

@@ -2576,6 +2576,7 @@ void                Compiler::compInitOptions(CORJIT_FLAGS* jitFlags)
     {
         printf("****** START compiling %s (MethodHash=%08x)\n",
                info.compFullName, info.compMethodHash());
+        printf("Generating code for %s %s\n", Target::g_tgtPlatformName, Target::g_tgtCPUName);
         printf("");         // in our logic this causes a flush
     }
 

src/jit/target.h

@@ -1823,6 +1823,7 @@ class Target
 {
 public:
     static const char *             g_tgtCPUName;
+    static const char *             g_tgtPlatformName;
 
     enum ArgOrder { ARG_ORDER_R2L, ARG_ORDER_L2R };
     static const enum ArgOrder      g_tgtArgOrder;

src/jit/utils.cpp

@@ -20,6 +20,21 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 
 #include "opcode.h"
 
+/*****************************************************************************/
+// Define the string platform name based on compilation #ifdefs. This is the
+// same code for all platforms, hence it is here instead of in the targetXXX.cpp
+// files.
+
+#ifdef PLATFORM_UNIX
+// Should we distinguish Mac? Can we?
+// Should we distinguish flavors of Unix? Can we?
+const char *                    Target::g_tgtPlatformName = "Unix";
+#else // !PLATFORM_UNIX
+const char *                    Target::g_tgtPlatformName = "Windows";
+#endif // !PLATFORM_UNIX
+
+/*****************************************************************************/
+
 #define DECLARE_DATA
 
 extern