libuvmem: usermode port of vmem(9)

The quantum cache is disabled, there is no uma.

Intent is to use this for resource allocation in bhyve(8), for start.
Addition of -luvmem to bhyve linking was done to test changes to share/mk.

Reviewed by:	bnovkov, markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D27220

share/mk/bsd.libnames.mk

@@ -171,6 +171,7 @@ LIBUSB?=	${LIBDESTDIR}${LIBDIR_BASE}/libusb.a
 LIBUSBHID?=	${LIBDESTDIR}${LIBDIR_BASE}/libusbhid.a
 LIBUTIL?=	${LIBDESTDIR}${LIBDIR_BASE}/libutil.a
 LIBUUTIL?=	${LIBDESTDIR}${LIBDIR_BASE}/libuutil.a
+LIBUVMEM?=	${LIBDESTDIR}${LIBDIR_BASE}/libuvmem.a
 LIBVERTO?=	${LIBDESTDIR}${LIBDIR_BASE}/libverto.a
 LIBVGL?=	${LIBDESTDIR}${LIBDIR_BASE}/libvgl.a
 LIBVMMAPI?=	${LIBDESTDIR}${LIBDIR_BASE}/libvmmapi.a

share/mk/src.libnames.mk

@@ -237,6 +237,7 @@ _LIBRARIES=	\
 		usb \
 		usbhid \
 		util \
+		uvmem \
 		uutil \
 		verto \
 		vmmapi \
@@ -491,6 +492,7 @@ _DP_fifolog=	z
 _DP_ipf=	kvm
 _DP_tpool=	spl
 _DP_uutil=	avl spl
+_DP_uvmem=	pthread
 _DP_zfs=	md pthread rt umem util uutil m avl bsdxml crypto geom nvpair \
 	z zfs_core zutil
 _DP_zfsbootenv= zfs nvpair
@@ -767,6 +769,9 @@ LIBSYS_PIC?=	${LIBSYS_PICDIR}/libsys_pic.a
 LIBSAMPLERATEDIR?=	${_LIB_OBJTOP}/lib/libsamplerate
 LIBSAMPLERATE?=	${LIBSAMPLERATEDIR}/libsamplerate${PIE_SUFFIX}.a
 
+LIBUVMEMDIR=	${OBJTOP}/lib/libuvmem
+LIBUVMEM?=	${LIBUVMEMDIR}/libuvmem${PIE_SUFFIX}.a
+
 # Define a directory for each library.  This is useful for adding -L in when
 # not using a --sysroot or for meta mode bootstrapping when there is no
 # Makefile.depend.  These are sorted by directory.