fakeroot: Fix segfault on ppc64le

When generating a filesystem image on a power10 build machine running
Ubuntu, we see a segfault when fakeroot is running chmod.

This has been reported and fixed upstream in Debian in version 1.26-1.2:

 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=995393#53

Add the same patch to resolve the segfault.

Signed-off-by: Joel Stanley <joel@jms.id.au>
[Arnout: add patch signoff and give proper name (check-package)]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/fakeroot/0001-fix-prototype-generation.patch

@@ -0,0 +1,61 @@
+Subject: Fix prototype generation for openat
+Author: Christoph Biedl <debian.axhn@manchmal.in-ulm.de>
+Date: 2021-12-30
+Bug-Debian: https://bugs.debian.org/995393
+Forwarded: Yes (implicitely)
+
+    As jrtc27 pointed out in IRC, ppc64el is more strict than other
+    architectures when it comes to va_arg handling:
+
+        it's that ppc64le uses the elfv2 abi, and for variadic calls you
+        must reserve space for a parameter save area
+
+    So enhance wrapawk to create a proper prototype and argument
+    handling although it's specific to the openat call. Also add the
+    missing documentation for the sixth column to wrapfunc.inp.
+
+Signed-off-by: Joel Stanley <joel@jms.id.au>
+
+--- a/wrapawk
++++ b/wrapawk
+@@ -37,7 +37,25 @@
+   argtype=$3;
+   argname=$4;
+   MACRO=$5;
+-  if(MACRO){
++  openat_extra=$6;
++  if(openat_extra){
++    print "  {(void(*))&next_" name ", \"" name "\"},"  > structfile;
++    print "extern " ret " (*next_" name ")" openat_extra ";" > headerfile;
++    print ret " (*next_" name ")" openat_extra "=tmp_" name ";"> deffile;
++
++    print ret " tmp_" name,  openat_extra "{"           > tmpffile;
++    print "  mode_t mode = 0;"                          > tmpffile;
++    print "  if (flags & O_CREAT) {"                    > tmpffile;
++    print "    va_list args;"                           > tmpffile;
++    print "    va_start(args, flags);"                  > tmpffile;
++    print "    mode = va_arg(args, int);"               > tmpffile;
++    print "    va_end(args);"                           > tmpffile;
++    print "  }"                                         > tmpffile;
++    print "  load_library_symbols();"                   > tmpffile;
++    print "  return  next_" name,  argname ";"          > tmpffile;
++    print "}"                                           > tmpffile;
++    print ""                                            > tmpffile;
++  } else if(MACRO){
+     print "  {(void(*))&NEXT_" MACRO "_NOARG, " name "_QUOTE},"  > structfile;
+     print "extern " ret " (*NEXT_" MACRO "_NOARG)" argtype ";" > headerfile;
+     print ret " (*NEXT_" MACRO "_NOARG)" argtype "=TMP_" MACRO ";"> deffile;
+--- a/wrapfunc.inp
++++ b/wrapfunc.inp
+@@ -9,8 +9,10 @@
+ /**/									  */
+ /* each line of this file lists 4 fields, seperated by a ";".		  */
+ /* The first field is the name of the wrapped function, then it's return  */
+-/* value. After that come the function arguments with types, and the last */
++/* value. After that come the function arguments with types, and the fifth */
+ /* field contains the function arguments without types.                   */
++/* A sixth field is a special needed when wrapping the openat syscall.    */
++/* Otherwise it's like the third (function arguments with types).         */
+ /**/
+ 
+ /* __*xstat are used on glibc systems instead of just *xstat. */