Fix Sparc/Linux host breakage by df70204db5

While i386, x86_64 and Sparc64/OpenBSD still worked after
df70204db5, Sparc32 and Sparc64 Linux hosts
broke.

Partially revert the commit: make the restored code conditional to
!CONFIG_USER_PIE.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

configure

@@ -2364,9 +2364,10 @@ if test "$target_softmmu" = "yes" ; then
 fi
 
 if test "$target_user_only" = "yes" -a "$static" = "no" -a \
-	"$user_pie" = "yes" ; then
+  "$user_pie" = "yes" ; then
   cflags="-fpie $cflags"
   ldflags="-pie $ldflags"
+  echo "CONFIG_USER_PIE=y" >> $config_mak
 fi
 
 if test "$target_softmmu" = "yes" -a \( \

linux-user/main.c

@@ -48,6 +48,27 @@ int have_guest_base;
 static const char *interp_prefix = CONFIG_QEMU_PREFIX;
 const char *qemu_uname_release = CONFIG_UNAME_RELEASE;
 
+/* for recent libc, we add these dummy symbols which are not declared
+   when generating a linked object (bug in ld ?) */
+#if ((__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 3)) && \
+     !defined(CONFIG_STATIC)) && !defined(CONFIG_USER_PIE)
+asm(".globl __preinit_array_start\n"
+    ".globl __preinit_array_end\n"
+    ".globl __init_array_start\n"
+    ".globl __init_array_end\n"
+    ".globl __fini_array_start\n"
+    ".globl __fini_array_end\n"
+    ".section \".rodata\"\n"
+    "__preinit_array_start:\n"
+    "__preinit_array_end:\n"
+    "__init_array_start:\n"
+    "__init_array_end:\n"
+    "__fini_array_start:\n"
+    "__fini_array_end:\n"
+    ".long 0\n"
+    ".previous\n");
+#endif
+
 /* XXX: on x86 MAP_GROWSDOWN only works if ESP <= address + 32, so
    we allocate a bigger stack. Need a better solution, for example
    by remapping the process stack directly at the right place */