Work around qemu static deadlock

Workaround issue pmbootstrap#1715.

This adds jemalloc package and brings back qemu package. These packages are compiled for x86 and x86_64 only. The binfmt_misc chroots on arm hosts are untested.

I tried to run an x86_64 pmbootstrap chroot on an arm device (ouya) but binfmt_misc doesn't seem to work. The /proc/sys/fs/binfmt_misc directory is empty.

temp/jemalloc/APKBUILD

+# Forked from Alpine, so we can build our qemu fork against jemalloc to
+# work around a deadlock while compiling mesa (pmbootstrap#1715)
+pkgname=jemalloc
+pkgver=5.1.0
+pkgrel=0
+pkgdesc="A general purpose malloc(3) implementation"
+url="http://jemalloc.net/"
+arch="x86 x86_64"
+license="BSD-2-Clause"
+subpackages="$pkgname-dev $pkgname-doc"
+source="$pkgname-$pkgver.tar.bz2::https://github.com/$pkgname/$pkgname/releases/download/$pkgver/$pkgname-$pkgver.tar.bz2
+	jemalloc-no-pprof.patch
+	"
+options="!check"
+
+build() {
+	cd "$builddir"
+	./configure \
+		--build=$CBUILD \
+		--host=$CHOST \
+		--prefix=/usr \
+		--sysconfdir=/etc \
+		--mandir=/usr/share/man \
+		--infodir=/usr/share/info \
+		--localstatedir=/var \
+		--disable-syscall
+	make
+}
+
+check() {
+	cd "$builddir"
+	make check
+}
+
+package() {
+	cd "$builddir"
+	make DESTDIR="$pkgdir" install
+}
+
+sha512sums="d9abebe54d303ca931b8c31c1033f23ff5fb060f2377ec8386f4d79c352e65c78ed34f680c352dac14f7d7115d10245782d553d988bc13df2eb34a2f0942ef6f  jemalloc-5.1.0.tar.bz2
+1e59e6e3bd98be3be12a2619acf213445906c1f70d5e06fbfb98c1409c93486934ab53d58709a05e0c109e5ba9eab16d2110163e173de22ef2dc969d1cde9274  jemalloc-no-pprof.patch"