Fix TableLookupTest on FreeBSD

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

Reviewed by: vitalybuka

Differential Revision: https://reviews.llvm.org/D125902

Author: zxombie

compiler-rt/test/fuzzer/TableLookupTest.cpp

@@ -22,7 +22,7 @@ const size_t N = 1 << 12;
 // 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