alloc/test: Check for TFI conflicts

This commit adds the check_tfi_usage function that checks the TFI
usage. It iterates through all TBFs, records on which PDCH it uses
which TFI and check for conflicts. It also checks the bits returned
by pdch->assigned_tfi(). The latter suffers from an bug in that
method (no separation of uplink and downlink), so a conditional
fprintf is used instead of an assertion. The method tfi_find_free
is checked for conflicts after allocations.

Sponsored-by: On-Waves ehf
diff --git a/tests/alloc/AllocTest.err b/tests/alloc/AllocTest.err
index af9b134..34ef756 100644
--- a/tests/alloc/AllocTest.err
+++ b/tests/alloc/AllocTest.err
@@ -1,6 +1,8 @@
 No TFI available.
+No TFI available.
 - Failed to allocate a TS, no USF available
 No TFI available.
+No TFI available.
 - Failed to allocate a TS, no USF available
 No TFI available.
 No TFI available.
@@ -17,3 +19,25 @@
 No TFI available.
 No TFI available.
 No TFI available.
+No TFI available.
+ERROR: TFI not marked as used in PDCH
+No TFI available.
+No TFI available.
+ERROR: TFI not marked as used in PDCH
+ERROR: TFI not marked as used in PDCH
+ERROR: TFI not marked as used in PDCH
+ERROR: TFI not marked as used in PDCH
+No TFI available.
+No TFI available.
+ERROR: TFI not marked as used in PDCH
+No TFI available.
+No TFI available.
+ERROR: TFI not marked as used in PDCH
+No TFI available.
+No TFI available.
+No TFI available.
+No TFI available.
+No TFI available.
+No TFI available.
+No TFI available.
+No TFI available.