Merge commit 'linux-user/linux-user-for-upstream' into staging

diff --cc configure
index fc664fc0a973dab9149dd76780b20dc9f7accd26,56dd489a3430f10b038b33e0a3f583a3fdcb3b33..b805f10297963cfdcecba68059842a449d2498e0
--- 1/configure
--- 2/configure
+++ b/configure
@@@ -1474,17 -1322,24 +1474,32 @@@ if compile_prog "" "" ; the
    splice=yes
  fi
  
+ # check if eventfd is supported
+ eventfd=no
+ cat > $TMPC << EOF
+ #include <sys/eventfd.h>
+ 
+ int main(void)
+ {
+     int efd = eventfd(0, 0);
+     return 0;
+ }
+ EOF
+ if compile_prog "" "" ; then
+   eventfd=yes
+ fi
+ 
  # Check if tools are available to build documentation.
 -if test "$build_docs" = "yes" -a \( ! -x "`which texi2html 2>/dev/null`" -o ! -x "`which pod2man 2>/dev/null`" \) ; then
 -  build_docs="no"
 +if test "$docs" != "no" ; then
 +  if test -x "`which texi2html 2>/dev/null`" -a \
 +          -x "`which pod2man 2>/dev/null`" ; then
 +    docs=yes
 +  else
 +    if test "$docs" = "yes" ; then
 +      feature_not_found "docs"
 +    fi
 +    docs=no
 +  fi
  fi
  
  # Search for bsawp_32 function