link_fdata does not support hardcoded offsets in no-LBR mode

For example, the below fails as the script tries to match it with the
LBR mode:

```
// RUN: link_fdata --no-lbr ...
// FDATA: 1 foo 0 10
```

Author: paschalis-mpeis

bolt/test/AArch64/fdata-nolbr.s

@@ -0,0 +1,18 @@
+# Check that using link_fdata tool in non-lbr mode allows using hardcoded
+# addresses for basic block offsets.
+
+# REQUIRES: system-linux
+
+# RUN: %clang %cflags -o %t %s
+# RUN: %clang %s %cflags -Wl,-q -o %t
+# RUN: not link_fdata --no-lbr %s %t %t.fdata 2>&1 | FileCheck %s
+
+  .text
+  .globl  foo
+  .type foo, %function
+foo:
+# FDATA: 1 foo 0 10
+    ret
+
+# Currently does not work on non-lbr mode.
+# CHECK: AssertionError: ERROR: wrong format/whitespaces must be escaped