tests: Add tests to ensure that we don't duplicate symbols in libraries

We have an issue where some symbols are exposed by both the tod library
and the public one, and this may lead to big issues like GType's being
defined multiple times.

So add a test checking whether this is working

See: 3v1n0/libfprint#1

libfprint/tod/tests/check-library-symbols.sh

@@ -0,0 +1,65 @@
+#!/bin/bash
+
+library1=$1
+library2=$2
+
+function cleanup_results() {
+    grep -F -w '.text' | cut -s -f2 | awk '{print $(NF)}'
+}
+
+function dump_exported_symbols() {
+    objdump -TC "$1" | cleanup_results
+}
+
+function dump_defined_symbols() {
+    objdump -t "$1" | cleanup_results
+}
+
+function in_array() {
+  local target=$1
+  shift
+
+  local i;
+  for i in "$@"; do
+    if [[ "$i" == "$target" ]]; then
+        return 0
+    fi
+  done
+
+  return 1
+}
+
+function is_fatal() {
+    if [[ "$1" == "fp_"* ]] || [[ "$1" == "fpi_"* ]]; then
+        return 0
+    fi
+    return 1
+}
+
+lib1_exported=($(dump_exported_symbols "$library1"))
+lib2_exported=($(dump_exported_symbols "$library2"))
+
+lib1_defined=("$(dump_defined_symbols "$library1")")
+lib2_defined=("$(dump_defined_symbols "$library2")")
+
+valid=true
+
+for f in ${lib1_exported[*]}; do
+    if in_array "$f" ${lib2_exported[*]}; then
+        echo "$f function exported in both $library1 and $library2"
+        if is_fatal "$f"; then
+            valid=false
+        fi
+    fi
+done
+
+for f in ${lib1_defined[*]}; do
+    if in_array "$f" ${lib2_defined[*]}; then
+        echo "$f function defined in both $library1 and $library2"
+        if is_fatal "$f"; then
+            valid=false
+        fi
+    fi
+done
+
+[[ "$valid" == true ]] && exit 0