extract LIBMTP_VERSION from header, and use that to set -DOLDMTP when building sendfirm, rather than trying to build each way

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19945 a1c6a512-1295-4272-9138-f99709370657
diff --git a/utils/MTP/Makefile b/utils/MTP/Makefile
index 6c709ec..8439f8b 100644
--- a/utils/MTP/Makefile
+++ b/utils/MTP/Makefile
@@ -1,11 +1,14 @@
 CFLAGS = -Wall
 LIBS = -lmtp
 OUTPUT = sendfirm
+EXTRA_CFLAGS = $(shell echo -e \
+	'\#include <libmtp.h>\nlibmtp version: LIBMTP_VERSION' | \
+	gcc -E -P - -o - | grep -q '^libmtp version: 0\.2' && echo '-DOLDMTP')
 
 all: $(OUTPUT)
 
 $(OUTPUT): sendfirm.c
-	gcc $(CFLAGS) $(LIBS) -o $(OUTPUT) sendfirm.c || gcc $(CFLAGS) $(LIBS) -DOLDMTP -o $(OUTPUT) sendfirm.c
+	gcc $(EXTRA_CFLAGS) $(CFLAGS) $(LIBS) -o $(OUTPUT) sendfirm.c
 
 $(OUTPUT).exe: sendfirm_win.c
 	mingw32-gcc $(CFLAGS) -o $(OUTPUT).exe sendfirm_win.c MTP_DLL.dll