patch to cope current texinfo version breaking firmware build

Apply this patch to have the firmware (toolchain actually) build again.

    Added a line to omit the erroneous build of gcc doc, as it would break the build right now.
    
    Signed-off-by: Martin Schröer <martin.schroeer@dfki.de>
```
--------------------------- toolchain/gcc/common.mk ---------------------------
index c18a330..a8d7ca1 100644
@@ -111,6 +111,7 @@ GCC_CONFIGURE:= \
 		--build=$(GNU_HOST_NAME) \
 		--host=$(GNU_HOST_NAME) \
 		--target=$(REAL_GNU_TARGET_NAME) \
+		MAKEINFO=missing \
 		--with-gnu-ld \
 		--enable-target-optspace \
 		--disable-libgomp \
```