[openwrt/openwrt] build: set up host command for egrep

[LEDE Commits]

nbd pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/6c29604438a0c2cbf95930244319c41d57756d7d

commit 6c29604438a0c2cbf95930244319c41d57756d7d
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Thu Aug 6 12:53:14 2020 +0200

    build: set up host command for egrep
    
    It is used for the kernel build and uses GNU specific features
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 include/prereq-build.mk | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/prereq-build.mk b/include/prereq-build.mk
index 83dad0f2dc..4637c6ca50 100644
--- a/include/prereq-build.mk
+++ b/include/prereq-build.mk
@@ -114,6 +114,10 @@ $(eval $(call SetupHostCommand,grep,Please install GNU 'grep', \
 	ggrep --version 2>&1 | grep GNU, \
 	grep --version 2>&1 | grep GNU))
 
+$(eval $(call SetupHostCommand,egrep,Please install GNU 'grep', \
+	gegrep --version 2>&1 | grep GNU, \
+	egrep --version 2>&1 | grep GNU))
+
 $(eval $(call SetupHostCommand,getopt, \
 	Please install an extended getopt version that supports --long, \
 	gnugetopt -o t --long test -- --test | grep '^ *--test *--', \