libpayload: bin/lpgcc allow to call without files

When building libflashrom ontop of libpayload, meson calls the lpgcc
wrapper with -xc but without a file to obtain information about the C
compiler. To make this work guard $_LIBGCC with -xnone in the lpgcc
wrapper. -xnone tells the compiler to interpret the following files of
libpayload by their suffix, not the privious given -x option.

Change-Id: I9e037ff44c0a6d0585d8a6f8aeabae6e651142e2
Signed-off-by: Thomas Heijligen <src@posteo.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70117
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/payloads/libpayload/bin/lpgcc b/payloads/libpayload/bin/lpgcc
index 5e418e8..35fa558 100755
--- a/payloads/libpayload/bin/lpgcc
+++ b/payloads/libpayload/bin/lpgcc
@@ -229,5 +229,5 @@
     # header to be placed below 0x2000 in the resulting image.  See:
     # http://www.gnu.org/software/grub/manual/multiboot/html_node/OS-image-format.html
 
-    $DEFAULT_CC $_LDFLAGS $HEAD_O $CMDLINE $_CFLAGS -lpayload $_LIBGCC
+    $DEFAULT_CC $_LDFLAGS $HEAD_O $CMDLINE $_CFLAGS -lpayload -xnone $_LIBGCC
 fi