Partially revert "build: -no-pie is no functional linker flag"

This partially reverts commit bbd2d5a8.

This commit was misguided and broke using --disable-pie on any distro
that enables PIE by default in their compiler driver, including Debian
and its derivatives. Whilst -no-pie is not a linker flag, it is a
compiler driver flag that ensures -pie is not automatically passed by it
to the linker. Without it, all compile_prog checks will fail as any code
built with the explicit -fno-pie will fail to link with the implicit
default -pie due to trying to use position-dependent relocations. The
only bug that needed fixing was LDFLAGS_NOPIE being used as a flag for
the linker itself in pc-bios/optionrom/Makefile.

Note this does not reinstate exporting LDFLAGS_NOPIE, as it is unused,
since the only previous use was the one that should not have existed. I
have also updated the comment for the -fno-pie and -no-pie checks to
reflect what they're actually needed for.

Fixes: bbd2d5a8
Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Michael Roth <michael.roth@amd.com>

configure

@@ -2192,9 +2192,11 @@ static THREAD int tls_var;
 int main(void) { return tls_var; }
 EOF
 
-# Check we support --no-pie first; we will need this for building ROMs.
+# Check we support -fno-pie and -no-pie first; we will need the former for
+# building ROMs, and both for everything if --disable-pie is passed.
 if compile_prog "-Werror -fno-pie" "-no-pie"; then
   CFLAGS_NOPIE="-fno-pie"
+  LDFLAGS_NOPIE="-no-pie"
 fi
 
 if test "$static" = "yes"; then
@@ -2210,6 +2212,7 @@ if test "$static" = "yes"; then
   fi
 elif test "$pie" = "no"; then
   CONFIGURE_CFLAGS="$CFLAGS_NOPIE $CONFIGURE_CFLAGS"
+  CONFIGURE_LDFLAGS="$LDFLAGS_NOPIE $CONFIGURE_LDFLAGS"
 elif compile_prog "-Werror -fPIE -DPIE" "-pie"; then
   CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
   CONFIGURE_LDFLAGS="-pie $CONFIGURE_LDFLAGS"