Remove redundant _GLIBCXX_USE_CXX11_ABI define

Author: kleisauke

build/posix.sh

@@ -39,14 +39,13 @@ mkdir ${DEPS}
 mkdir ${TARGET}
 
 # Default optimisation level is for binary size (-Os)
-# Overriden to performance (-O3) for select dependencies that benefit
+# Overridden to performance (-O3) for select dependencies that benefit
 export FLAGS+=" -Os -fPIC"
 
-# Force "new" C++11 ABI compliance
 # Remove async exception unwind/backtrace tables
 # Allow linker to remove unused sections
 if [ "$LINUX" = true ]; then
-  export FLAGS+=" -D_GLIBCXX_USE_CXX11_ABI=1 -fno-asynchronous-unwind-tables -ffunction-sections -fdata-sections"
+  export FLAGS+=" -fno-asynchronous-unwind-tables -ffunction-sections -fdata-sections"
 fi
 
 # Common build paths and flags
@@ -437,6 +436,8 @@ cd ${TARGET}/lib
 if [ "$LINUX" = true ]; then
   # Check that we really linked with -z nodelete
   readelf -Wd ${VIPS_CPP_DEP} | grep -qF NODELETE || (echo "$VIPS_CPP_DEP was not linked with -z nodelete" && exit 1)
+  # Check that we really use the "new" C++11 ABI
+  readelf -Ws ${VIPS_CPP_DEP} | c++filt | grep -qF "::__cxx11::" || (echo "$VIPS_CPP_DEP mistakenly uses the C++03 ABI" && exit 1)
 fi
 copydeps ${VIPS_CPP_DEP} ${TARGET}/lib-filtered