fix build error due to gcc 10

error:
/usr/bin/ld: fping-socket4.o:/home/abuild/rpmbuild/BUILD/fping-4.2/src/fping.h:14: multiple definition of `random_data_flag'; fping-fping.o:/home/abuild/rpmbuild/BUILD/fping-4.2/src/fping.h:14: first defined here

fping.spec

@@ -2,11 +2,12 @@
 
 Name:    fping
 Version: 4.2
-Release: 1
+Release: 2
 Summary: fping is a program to send ICMP echo probes to network hosts
 License: BSD like
 URL:	 http://www.fping.org/
 Source0: http://www.fping.org/dist/%{name}-%{version}.tar.gz
+Patch0:  gcc-10.patch
 
 BuildRequires: 	gcc
 
@@ -15,6 +16,7 @@ fping is a program to send ICMP echo probes to network hosts, similar to ping, b
 
 %prep
 %setup -q -n %{name}-%{version}/
+%patch0 -p1
 
 %build
 %configure
@@ -37,6 +39,9 @@ fping is a program to send ICMP echo probes to network hosts, similar to ping, b
 %{_mandir}/*
 
 %changelog
+* Fri Jul 30 2021 linjiaxin5 <linjiaxin5@huawei.com> - 4.2-2
+- Fix failure caused by GCC upgrade to 10
+
 * Sun Mar 29 2020 Wei Xiong <myeuler@163.com>
 - Package init
 

gcc-10.patch

@@ -0,0 +1,11 @@
+--- a/src/fping.h	2021-08-03 15:44:55.282990658 +0800
++++ b/src/fping.h	2021-08-03 15:45:15.519338280 +0800
+@@ -11,7 +11,7 @@
+ void crash_and_burn( char *message );
+ void errno_crash_and_burn( char *message );
+ int in_cksum( unsigned short *p, int n );
+-int random_data_flag;
++extern int random_data_flag;
+ 
+ /* socket.c */
+ int  open_ping_socket_ipv4();