nptl: Use vfork on MMU-less for system()
nptl: Use vfork on MMU-less for system()

	* libc/stdlib/system.c (FORK): Map to vfork if __ARCH_USE_MMU__
	is defined.

Signed-off-by: Mickaël Guêné <fd4c850767532186e170673aca49b5c51d48c53c@st.com>
Signed-off-by: Christophe Lyon <0ec1b8ee85d9250d253c392c5d5101068ac5d5d3@st.com>

wbx-github/uclibc-ng,wbx-github/uclibc-ng,wbx-github/uclibc-ng,kraj/uclibc-ng,wbx-github/uclibc-ng,kraj/uclibc-ng,kraj/uclibc-ng,kraj/uclibc-ng