Problem is fixed in protobuf upstream (3.2.0+).

With Android NDK 16.1 (gcc):

FAILED: 3rdparty/protobuf/CMakeFiles/libprotobuf.dir/src/google/protobuf/util/internal/type_info.cc.o
/toolchains/x86-4.9/prebuilt/linux-x86_64/bin/i686-linux-android-g++ --sysroot=/sysroot -DHAVE_PTHREAD=1 -D__OPENCV_BUILD=1 -I3rdparty/protobuf/src -I3rdparty/ippicv/ippicv_lnx/include -I3rdparty/ippicv/ippiw_lnx/include -I. -isystem /sources/cxx-stl/llvm-libc++/include -isystem /sources/android/support/include -isystem /sources/cxx-stl/llvm-libc++abi/include -isystem /sysroot/usr/include/i686-linux-android -D__ANDROID_API__=21 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -mstackrealign -Wa,--noexecstack -Wformat -Werror=format-security -std=c++11 -fno-strict-aliasing -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Winit-self -Wpointer-arith -Wuninitialized -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -march=i686 -fomit-frame-pointer -msse -msse2 -mfpmath=sse -fvisibility=hidden -fvisibility-inlines-hidden -Wno-deprecated -Wno-missing-declarations -Wno-shadow -Wno-unused-parameter -Wno-unused-local-typedefs -Wno-sign-compare -Wno-sign-promo -Wno-undef -Wno-ignored-qualifiers -Wno-extra -Wno-unused-function -O2 -DNDEBUG -DNDEBUG -fPIC -MD -MT 3rdparty/protobuf/CMakeFiles/libprotobuf.dir/src/google/protobuf/util/internal/type_info.cc.o -MF 3rdparty/protobuf/CMakeFiles/libprotobuf.dir/src/google/protobuf/util/internal/type_info.cc.o.d -o 3rdparty/protobuf/CMakeFiles/libprotobuf.dir/src/google/protobuf/util/internal/type_info.cc.o -c 3rdparty/protobuf/src/google/protobuf/util/internal/type_info.cc

3rdparty/protobuf/src/google/protobuf/util/internal/type_info.cc:126:33: error: reference to 'map' is ambiguous
   static void DeleteCachedTypes(map<StringPiece, T>* cached_types) {
                                 ^