[BOLT][AArch64] Instrumentation for static binaries doesn't work in reloc mode.

On AArch64, when trying to instrument a static binary that has relocation
data BOLT would crash as it misses `createDummyReturnFunction` function.

Author: paschalis-mpeis

bolt/test/AArch64/dummy-return.test

@@ -0,0 +1,6 @@
+REQUIRES: system-linux
+
+RUN: %clang %p/../Inputs/main.c -o %t -Wl,-q -static
+RUN: not llvm-bolt -instrument -instrumentation-sleep-time=1 %t -o %t.instr 2>&1 | FileCheck %s
+
+CHECK: not implemented

bolt/test/Inputs/main.c

@@ -0,0 +1,3 @@
+// dummy function just for emitting relocations  to the linker.
+int foo() { return 0; }
+int main(int argc, char **argv) { return foo() + 1; }