Install on ruby 2.3 fails

[gwww]

Compile error:

/usr/bin/clang -I. -I/Users/Glenn/.rvm/rubies/ruby-2.3.0/include/ruby-2.3.0/x86_64-darwin15 -I/Users/Glenn/.rvm/rubies/ruby-2.3.0/include/ruby-2.3.0/ruby/backward -I/Users/Glenn/.rvm/rubies/ruby-2.3.0/include/ruby-2.3.0 -I. -I/usr/local/opt/libyaml/include -I/usr/local/opt/readline/include -I/usr/local/opt/libksba/include -I/usr/local/opt/openssl/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -D_DARWIN_UNLIMITED_SELECT -D_REENTRANT -fno-common -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wshorten-64-to-32 -Wimplicit-function-declaration -Wdivision-by-zero -Wdeprecated-declarations -Wextra-tokens -fno-common -pipe -std=c99 -Wall -Werror -pedantic -ObjC -DNOT_MACRUBY -o screen_recorder.o -c screen_recorder.c
In file included from screen_recorder.c:4:
In file included from /Users/Glenn/.rvm/rubies/ruby-2.3.0/include/ruby-2.3.0/ruby.h:33:
In file included from /Users/Glenn/.rvm/rubies/ruby-2.3.0/include/ruby-2.3.0/ruby/ruby.h:29:
In file included from /Users/Glenn/.rvm/rubies/ruby-2.3.0/include/ruby-2.3.0/ruby/defines.h:68:
/Users/Glenn/.rvm/rubies/ruby-2.3.0/include/ruby-2.3.0/ruby/missing.h:256:5: error:
implicit declaration of function 'memset_s' is invalid in C99
[-Werror,-Wimplicit-function-declaration]
memset_s(b, len, 0, len);
^
/Users/Glenn/.rvm/rubies/ruby-2.3.0/include/ruby-2.3.0/ruby/missing.h:256:5: note: did
you mean 'memset'?
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/string.h:74:7: note:
'memset' declared here
void *memset(void *, int, size_t);

[gwww]

Removing -std=c99 fixes the error.

Similar problem with another gem: eagletmt/faml#47