Name the default switch (used for testing) in fuzz/default.switch.

fuzz/Makefile

-SWITCH := 4.11.1+afl
-EXE := src/Main.exe
+# The switch that is used for testing is named in the file default.switch.
+SWITCH := $(shell cat default.switch)
 
+EXE := src/Main.exe
 
 # This line is somewhat problematic, as it assumes that ocamlfind and
 # monolith are installed in the current switch, whatever it is.

fuzz/default.switch

+4.11.1+afl