[libfuzzer] Fix compile error from missing courgette_fuzzer.cc include.

https://codereview.chromium.org/1629703002/ missed a spot and broke
build with libfuzzer. This fixes it.

[email protected]
NOTRY=true

Review URL: https://codereview.chromium.org/1654503002

Cr-Commit-Position: refs/heads/master@{#372475}
diff --git a/testing/libfuzzer/fuzzers/courgette_fuzzer.cc b/testing/libfuzzer/fuzzers/courgette_fuzzer.cc
index 7b7ac08..43063a9 100644
--- a/testing/libfuzzer/fuzzers/courgette_fuzzer.cc
+++ b/testing/libfuzzer/fuzzers/courgette_fuzzer.cc
@@ -6,6 +6,7 @@
 #include "courgette/assembly_program.h"
 #include "courgette/courgette.h"
 #include "courgette/encoded_program.h"
+#include "courgette/program_detector.h"
 
 // Entry point for LibFuzzer.
 extern "C" int LLVMFuzzerTestOneInput(const unsigned char* data, size_t size) {