[PATCH] build system: fix linking on Red Hat systems

[Ron Yorston]

Commit 77216c368 (Fix non-Linux builds) made linking with libresolv
conditional on the output of 'gcc -dumpmachine' containing 'gnu'.

This broke builds on Red Hat systems (Fedora, RHEL) and derivatives
(CentOS, Rocky).  Such systems report a machine type of the form
'x86_64-redhat-linux'.

Check for 'linux' as well as 'gnu'.

Signed-off-by: Ron Yorston <rmy at pobox.com>
---
 Makefile.flags | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Makefile.flags b/Makefile.flags
index 50137a78e..e484ab6c7 100644
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -186,6 +186,8 @@ endif
 ifeq ($(CONFIG_FEATURE_NSLOOKUP_BIG),y)
 ifneq (,$(findstring gnu,$(shell $(CC) $(CFLAGS) -dumpmachine)))
 LDLIBS += resolv
+else ifneq (,$(findstring linux,$(shell $(CC) $(CFLAGS) -dumpmachine)))
+LDLIBS += resolv
 endif
 endif
 
-- 
2.38.1