Add definitions for symbols in unit test for prctl.

Follow up to: https://reviews.llvm.org/D122851

Differential Revision: https://reviews.llvm.org/D123395

compiler-rt/test/sanitizer_common/TestCases/Linux/prctl.cpp

@@ -5,6 +5,14 @@
 #include <stdint.h>
 #include <sys/prctl.h>
 
+#ifndef PR_SCHED_CORE
+#  define PR_SCHED_CORE 62
+#endif
+
+#ifndef PR_SCHED_CORE_CREATE
+#  define PR_SCHED_CORE_CREATE 1
+#endif
+
 int main() {
 
   int res;