Move API levels from `uint32_t` to `int`.

(cherrypick of a6c71a09670ca636cca5cfea9d74b03a951e2b5e.)

Bug: N/A
Test: builds
Change-Id: I9c414e30e3c4fe2a4e16a2fe4ce18eae85fe4844
diff --git a/linker/linker_config.h b/linker/linker_config.h
index 24c44f4..49739ee 100644
--- a/linker/linker_config.h
+++ b/linker/linker_config.h
@@ -140,7 +140,7 @@
     return it == namespace_configs_map_.end() ? nullptr : it->second;
   }
 
-  uint32_t target_sdk_version() const {
+  int target_sdk_version() const {
     return target_sdk_version_;
   }
 
@@ -159,7 +159,7 @@
  private:
   void clear();
 
-  void set_target_sdk_version(uint32_t target_sdk_version) {
+  void set_target_sdk_version(int target_sdk_version) {
     target_sdk_version_ = target_sdk_version;
   }
 
@@ -167,7 +167,7 @@
 
   std::vector<std::unique_ptr<NamespaceConfig>> namespace_configs_;
   std::unordered_map<std::string, NamespaceConfig*> namespace_configs_map_;
-  uint32_t target_sdk_version_;
+  int target_sdk_version_;
 
   DISALLOW_COPY_AND_ASSIGN(Config);
 };