[fuzzer] Fix TableLookupTest on FreeBSD

[andrew]

Summary

As with Linux placce the Counters array in the __libfuzzer_extra_counters
section. This fixes the test on FreeBSD.

compiler-rt/test/fuzzer/TableLookupTest.cpp

 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 // Make sure the fuzzer eventually finds all possible values of a variable
 // within a range.
 #include <cassert>
 #include <cstdint>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <set>
 
 const size_t N = 1 << 12;
 
 // Define an array of counters that will be understood by libFuzzer
 // as extra coverage signal. The array must be:
 //  * uint8_t
 //  * in the section named __libfuzzer_extra_counters.
 // The target code may declare more than one such array.
 //
 // Use either `Counters[Idx] = 1` or `Counters[Idx]++;`
 // depending on whether multiple occurrences of the event 'Idx'
 // is important to distinguish from one occurrence.
-#ifdef __linux__
+#if defined(__linux__) || defined(__FreeBSD__)
 __attribute__((section("__libfuzzer_extra_counters")))
 #endif
 #ifdef _WIN32
 #  pragma section(".data$__libfuzzer_extra_counters")
 __declspec(allocate(".data$__libfuzzer_extra_counters"))
 #endif
     static uint8_t Counters[N];