[openwrt/openwrt] build: require rsync

[LEDE Commits]

stintel pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/0ba83a757728185eabd965e07331508923cca825

commit 0ba83a757728185eabd965e07331508923cca825
Author: Stijn Tintel <stijn at linux-ipv6.be>
AuthorDate: Fri Dec 4 19:16:26 2020 +0200

    build: require rsync
    
    It seems to be required to build toolchain/kernel-headers.
    
    Signed-off-by: Stijn Tintel <stijn at linux-ipv6.be>
---
 README.md               | 2 +-
 include/prereq-build.mk | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 8d9a616ac5..21acbf4b80 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ documentation.
 
 ```
 gcc binutils bzip2 flex python3 perl make find grep diff unzip gawk getopt
-subversion libz-dev libc-dev
+subversion libz-dev libc-dev rsync
 ```
 
 ### Quickstart
diff --git a/include/prereq-build.mk b/include/prereq-build.mk
index e7314b253b..5045fabdfb 100644
--- a/include/prereq-build.mk
+++ b/include/prereq-build.mk
@@ -170,6 +170,9 @@ $(eval $(call SetupHostCommand,git,Please install Git (git-core) >= 1.7.12.2, \
 $(eval $(call SetupHostCommand,file,Please install the 'file' package, \
 	file --version 2>&1 | grep file))
 
+$(eval $(call SetupHostCommand,rsync,Please install 'rsync', \
+	rsync --version </dev/null))
+
 $(STAGING_DIR_HOST)/bin/mkhash: $(SCRIPT_DIR)/mkhash.c
 	mkdir -p $(dir $@)
 	$(CC) -O2 -I$(TOPDIR)/tools/include -o $@ $<