Make it return a _const_ char*.

Python/getcompiler.c

@@ -51,7 +51,7 @@ PERFORMANCE OF THIS SOFTWARE.
 
 #endif /* !COMPILER */
 
-char *
+const char *
 Py_GetCompiler()
 {
 	return COMPILER;

Python/getplatform.c

@@ -35,7 +35,7 @@ PERFORMANCE OF THIS SOFTWARE.
 #define PLATFORM "unknown"
 #endif
 
-char *
+const char *
 Py_GetPlatform()
 {
 	return PLATFORM;

Python/getversion.c

@@ -35,9 +35,6 @@ PERFORMANCE OF THIS SOFTWARE.
 
 #include "patchlevel.h"
 
-extern const char *Py_GetCompiler();
-extern const char *Py_GetBuildInfo();
-
 const char *
 Py_GetVersion()
 {