Use -Werror in hardware/libhardware_legacy

* Remove unused local variable or suppress the warning.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I4d7b4f2e9e7e6c60d8bfc209f47e6f1d33720165

Android.bp

@@ -17,6 +17,7 @@ cc_library {
     name: "libpower",
 
     srcs: ["power.c"],
+    cflags: ["-Wall", "-Werror"],
     export_include_dirs: ["include"],
     shared_libs: ["libcutils", "liblog"],
     vendor_available: true,
@@ -48,6 +49,8 @@ cc_library_shared {
 
     cflags: [
         "-DQEMU_HARDWARE",
+        "-Wall",
+        "-Werror",
         "-Wno-unused-parameter",
         "-Wno-gnu-designator",
     ],

audio/Android.bp

@@ -13,7 +13,10 @@ cc_library_static {
     name: "libaudiohw_legacy",
     static_libs: ["libmedia_helper"],
     cflags: [
+        "-Wall",
+        "-Werror",
         "-Wno-unused-parameter",
+        "-Wno-unused-variable",
         "-Wno-gnu-designator",
     ],
 

power.c

@@ -91,7 +91,6 @@ acquire_wake_lock(int lock, const char* id)
     if (g_error) return g_error;
 
     int fd;
-    size_t len;
     ssize_t ret;
 
     if (lock != PARTIAL_WAKE_LOCK) {