[Dependency Scanning] Provide libSwiftScan API to dispose of a string ref

Previously no API returned a raw 'swiftscan_string_ref_t' directly so this was not needed.
However, 'swiftscan_compiler_target_info_query' returns a string directly, which the clients need to clean up.

Author: artemcm

include/swift-c/DependencyScan/DependencyScan.h

@@ -272,6 +272,9 @@ swiftscan_scan_invocation_get_argv(swiftscan_scan_invocation_t invocation);
 SWIFTSCAN_PUBLIC void
 swiftscan_string_set_dispose(swiftscan_string_set_t *set);
 
+SWIFTSCAN_PUBLIC void
+swiftscan_string_dispose(swiftscan_string_ref_t string);
+
 SWIFTSCAN_PUBLIC void
 swiftscan_dependency_graph_dispose(swiftscan_dependency_graph_t result);
 

tools/libSwiftScan/libSwiftScan.cpp

@@ -27,12 +27,6 @@ DEFINE_SIMPLE_CONVERSION_FUNCTIONS(DependencyScanningTool, swiftscan_scanner_t)
 
 //=== Private Cleanup Functions -------------------------------------------===//
 
-/// Free the given string.
-void swiftscan_string_dispose(swiftscan_string_ref_t string) {
-  if (string.data)
-    free(const_cast<void *>(string.data));
-}
-
 void swiftscan_dependency_info_details_dispose(
     swiftscan_module_details_t details) {
   swiftscan_module_details_s *details_impl = details;
@@ -446,6 +440,11 @@ swiftscan_scan_invocation_get_argv(swiftscan_scan_invocation_t invocation) {
 
 //=== Public Cleanup Functions --------------------------------------------===//
 
+void swiftscan_string_dispose(swiftscan_string_ref_t string) {
+  if (string.data)
+    free(const_cast<void *>(string.data));
+}
+
 void swiftscan_string_set_dispose(swiftscan_string_set_t *set) {
   for (unsigned SI = 0, SE = set->count; SI < SE; ++SI)
     swiftscan_string_dispose(set->strings[SI]);

tools/libSwiftScan/libSwiftScan.exports

@@ -46,6 +46,7 @@ swiftscan_dependency_graph_create
 swiftscan_batch_scan_result_create
 swiftscan_import_set_create
 swiftscan_scanner_create
+swiftscan_string_dispose
 swiftscan_string_set_dispose
 swiftscan_scan_invocation_dispose
 swiftscan_batch_scan_input_dispose