Suppress ordered-compare-function-pointers warning

The affected code are using function pointer comparison for legitimate
purposes. Suppress the warning.

Bug: 197230471
Test: build
Change-Id: Ief9d720ee39b8be6467e127c0d3f14b026eaf9ed
diff --git a/camera/ndk/impl/ACameraManager.h b/camera/ndk/impl/ACameraManager.h
index ccbfaa9..da887a2 100644
--- a/camera/ndk/impl/ACameraManager.h
+++ b/camera/ndk/impl/ACameraManager.h
@@ -139,6 +139,8 @@
             return !(*this == other);
         }
         bool operator < (const Callback& other) const {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wordered-compare-function-pointers"
             if (*this == other) return false;
             if (mContext != other.mContext) return mContext < other.mContext;
             if (mPhysicalCamAvailable != other.mPhysicalCamAvailable) {
@@ -152,6 +154,7 @@
             }
             if (mAvailable != other.mAvailable) return mAvailable < other.mAvailable;
             return mUnavailable < other.mUnavailable;
+#pragma GCC diagnostic pop
         }
         bool operator > (const Callback& other) const {
             return (*this != other && !(*this < other));