Re-enable mmap test in configure & fix the code build again

- this stuff has been disabled for years, lets see what breaks...

configure.ac

@@ -514,10 +514,7 @@ AC_TYPE_SIZE_T
 
 dnl Checks for library functions.
 AC_FUNC_VPRINTF
-dnl XXX don't want to re-enable code that's been unused for years at this
-dnl point, but should offer good performance improvements, check after
-dnl 4.4.2.1...
-dnl AC_FUNC_MMAP
+AC_FUNC_MMAP
 
 AC_CHECK_FUNCS(mtrace)
 AC_CHECK_FUNCS(strndup)

lib/fsm.c

@@ -880,6 +880,7 @@ static int writeFile(FSM_t fsm, int writeData)
 	char * rdbuf = NULL;
 	void * mapped = (void *)-1;
 	size_t nmapped;
+	int xx;
 #endif
 
 	rc = fsmNext(fsm, FSM_ROPEN);

rpmio/rpmfileutil.c

@@ -155,6 +155,7 @@ int rpmDoDigest(pgpHashAlgo algo, const char * fn,int asAscii,
     case URL_IS_UNKNOWN:
 #ifdef HAVE_MMAP
       if (pid == 0) {
+	int xx;
 	DIGEST_CTX ctx;
 	void * mapped;