futex.2, syscalls.2, vmsplice.2, bpf-helpers.7: wfix: Write consistently 'user space' instead of 'userspace'

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/futex.2

@@ -1018,7 +1018,7 @@ user space atomically by setting the futex value to 0.
 .\"     retry:
 .\"
 .\"     	/*
-.\"     	 * Owner might have unlocked in userspace before we
+.\"     	 * Owner might have unlocked in user space before we
 .\"     	 * were able to set the waiter bit.
 .\"              */
 .\"             if (atomic_acquire(futex) == SUCCESS) {
@@ -1147,7 +1147,7 @@ but the kernel can fix this up and acquire the futex.
 .\"	in user space would fail, so kernel has to clean up.)
 .\" Darren Hart (Oct 2015):
 .\"     The trylock in the kernel has more state, so it can independently
-.\"     verify the  flags that userspace must trust implicitly.
+.\"     verify the flags that user space must trust implicitly.
 .IP
 The
 .IR uaddr2 ,

man2/syscalls.2

@@ -224,7 +224,7 @@ T}
 .\" \fBcmpxchg\fP(2)	2.6.12	T{
 .\" ARM, syscall constant never was
 .\" .br
-.\" exposed to userspace, in-kernel
+.\" exposed to user space, in-kernel
 .\" .br
 .\" definition had \fB__ARM_NR\fP prefix,
 .\" .br

man2/vmsplice.2

@@ -181,7 +181,7 @@ this limit is 1024.
 .\" commit 6a14b90bb6bc7cd83e2a444bf457a2ea645cbfe7
 .BR vmsplice ()
 really supports true splicing only from user memory to a pipe.
-In the opposite direction, it actually just copies the data to userspace.
+In the opposite direction, it actually just copies the data to user space.
 But this makes the interface nice and symmetric and enables people to build on
 .BR vmsplice ()
 with room for future improvement in performance.

man7/bpf-helpers.7

@@ -3020,7 +3020,7 @@ void bpf_sys_open(struct pt_regs *ctx)
                                           ctx\->di);
 
         // Consume buf, for example push it to
-        // userspace via bpf_perf_event_output(); we
+        // user space via bpf_perf_event_output(); we
         // can use res (the string length) as event
         // size, after checking its boundaries.
 }