configure: Support -static-pie if requested

Recent toolchains support static and pie at the same time.

As with normal dynamic builds, allow --static to default to PIE
if supported by the toolchain.  Allow --enable/--disable-pie to
override the default.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
v2: Fix --disable-pie --static
v3: Update for QEMU_LDFLAGS.

configure

@@ -1067,7 +1067,6 @@ for opt do
   ;;
   --static)
     static="yes"
-    QEMU_LDFLAGS="-static $QEMU_LDFLAGS"
     QEMU_PKG_CONFIG_FLAGS="--static $QEMU_PKG_CONFIG_FLAGS"
   ;;
   --mandir=*) mandir="$optarg"
@@ -2089,11 +2088,6 @@ if test "$static" = "yes" ; then
   if test "$modules" = "yes" ; then
     error_exit "static and modules are mutually incompatible"
   fi
-  if test "$pie" = "yes" ; then
-    error_exit "static and pie are mutually incompatible"
-  else
-    pie="no"
-  fi
 fi
 
 # Unconditional check for compiler __thread support
@@ -2124,7 +2118,18 @@ if compile_prog "-Werror -fno-pie" "-no-pie"; then
   LDFLAGS_NOPIE="-no-pie"
 fi
 
-if test "$pie" = "no"; then
+if test "$static" = "yes"; then
+  if test "$pie" != "no" && compile_prog "-fPIE -DPIE" "-static-pie"; then
+    QEMU_CFLAGS="-fPIE -DPIE $QEMU_CFLAGS"
+    QEMU_LDFLAGS="-static-pie $QEMU_LDFLAGS"
+    pie="yes"
+  elif test "$pie" = "yes"; then
+    error_exit "-static-pie not available due to missing toolchain support"
+  else
+    QEMU_LDFLAGS="-static $QEMU_LDFLAGS"
+    pie="no"
+  fi
+elif test "$pie" = "no"; then
   QEMU_CFLAGS="$CFLAGS_NOPIE $QEMU_CFLAGS"
   QEMU_LDFLAGS="$LDFLAGS_NOPIE $QEMU_LDFLAGS"
 elif compile_prog "-fPIE -DPIE" "-pie"; then