Error building on OS X El Capitan: window.c:1078:6: error: conflicting types for 'execvpe'

Hi,

I'm trying to build Git HEAD of screen on OS X El Capital (latest
version: 10.11.4) and getting the following error output - help
appreciated:

$ make
AWK=awk srcdir=. sh ./term.sh
AWK=awk CC="gcc -g -O2 -Wall -Wextra -std=c11" srcdir=. sh ./comm.sh
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 screen.c -o screen.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 ansi.c -o ansi.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 fileio.c -o fileio.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 mark.c -o mark.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 misc.c -o misc.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 resize.c -o resize.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 socket.c -o socket.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 search.c -o search.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 tty.c -o tty.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 term.c -o term.o
gcc -c  -iquote. -DETCSCREENRC='"/usr/local/etc/screenrc"'
-DSCREENENCODINGS='"/usr/local/share/screen/utf8encodings"' -g -O2
-Wall -Wextra -std=c11 window.c -o window.o
window.c:1067:3: warning: implicit declaration of function 'execvpe'
is invalid in C99 [-Wimplicit-function-declaration]
                execvpe(proc, args, NewEnv);
                ^
window.c:1078:6: error: conflicting types for 'execvpe'
void execvpe(char *prog, char **args, char **env)
     ^
window.c:1067:3: note: previous implicit declaration is here
                execvpe(proc, args, NewEnv);
                ^
1 warning and 1 error generated.
make: *** [window.o] Error 1