libvpx: Pull from upstream

source/libvpx/build/make/configure.sh

 #!/bin/sh
 ##
 ##  configure.sh
 ##
 ##  This script is sourced by the main configure script and contains
 ##  utility functions and other common bits that aren't strictly libvpx
 ##  related.
 ##
 ##  This build system is based in part on the FFmpeg configure script.
 ##
@@ skipping 1204 matching lines @@
         fi
     if [ -n "${tune_asflags}" ]; then
             check_add_asflags ${tune_asflags}${tune_cpu} || \
                 die "Requested CPU '${tune_cpu}' not supported by assembler"
         fi
     if [ -z "${tune_cflags}${tune_asflags}" ]; then
             log_echo "Warning: CPU tuning not supported by this toolchain"
         fi
     fi
 
-    enabled debug && check_add_cflags -g && check_add_ldflags -g
+    if enabled debug; then
+        check_add_cflags -g && check_add_ldflags -g
+    else
+        check_add_cflags -DNDEBUG
+    fi
+
     enabled gprof && check_add_cflags -pg && check_add_ldflags -pg
     enabled gcov &&
         check_add_cflags -fprofile-arcs -ftest-coverage &&
         check_add_ldflags -fprofile-arcs -ftest-coverage
 
     if enabled optimizations; then
         if enabled rvct; then
             enabled small && check_add_cflags -Ospace || check_add_cflags -Otime
         else
             enabled small && check_add_cflags -O2 ||  check_add_cflags -O3
@@ skipping 154 matching lines @@
     # Prepare the PWD for building.
     for f in ${OOT_INSTALLS}; do
             install -D "${source_path}/$f" "$f"
     done
     fi
     cp "${source_path}/build/make/Makefile" .
 
     clean_temp_files
     true
 }