Unfortunately, CC ?= afl-gcc doesn't work. This is because CC has a
default value (of "cc"), and the ?= operator only assigns a value if the
variable previously had none. "make" currently compiles with cc.
In this patch, I implemented the more elaborate way to achieve what was
probably intended: "make" will use afl-gcc now, and "make CC=foo" will
compile with "foo".
The experimental multi-packet mode splits input bytes depending on a length
decoded from the first 2 bytes and does that until the end of input.
To use this mode, compile with "make D=-DLWIP_FUZZ_MULTI_PACKET"
Signed-off-by: goldsimon <goldsimon@gmx.de>
