[PATCH] Resurrect x86-linux build.

[Janneke Nieuwenhuizen]

This avoids using system headers, which may result in

    kern/strings.c: In function 'strchr':
    kern/strings.c:188:32: error: 'NULL' undeclared (first use in this function)

    In file included from util/atoi.c:77:
    ./util/atoi.h:65:29: error: unknown type name 'u_char'

    device/net_io.c: In function 'bpf_do_filter':
    device/net_io.c:1636:34: error: 'u_int' undeclared (first use in this 
function); did you mean 'int'?

    In file included from device/subrs.c:36:
    ./device/if_ether.h:43:9: error: unknown type name 'u_char'
       43 |         u_char  ether_dhost[6];

    ./linux/dev/include/linux/fs.h:304:5: error: unknown type name 'loff_t'
      304 |     loff_t f_pos;

This is a follow-up to commit
    d5e5dd3401ea0d0475aa830c2171be5b8a72f4fa
    Update configure.ac so that we don't need glibc when running ./configure.
---
 Makefile.am | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index e31a875d..ad38249b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -43,7 +43,7 @@ AM_LDFLAGS =
 
 GCC_INSTALL = $(shell LANG=C $(CC) -print-search-dirs | sed -n -e 's/install: 
\(.*\)/\1/p')
 AM_CPPFLAGS += \
-       -imacros config.h -I $(GCC_INSTALL)/include
+       -nostdinc -imacros config.h -I $(GCC_INSTALL)/include
 
 AM_CPPFLAGS += \
        -I$(systype) \
-- 
2.41.0