Otherwise you might get "-dirty" in the pc: version

--- libslirp-4.3.0/build-aux/git-version-gen	2020-04-23 06:09:44.166262600 -0500
+++ libslirp-4.3.0/build-aux/git-version-gen	2020-04-24 15:08:09.450004079 -0500
@@ -133,19 +133,6 @@ fi
 
 v=`echo "$v" |sed 's/^v//'`
 
-# Don't declare a version "dirty" merely because a time stamp has changed.
-git update-index --refresh > /dev/null 2>&1
-
-dirty=`sh -c 'git diff-index --name-only HEAD' 2>/dev/null` || dirty=
-case "$dirty" in
-    '') ;;
-    *) # Append the suffix only if there isn't one already.
-	case $v in
-	  *-dirty) ;;
-	  *) v="$v-dirty" ;;
-	esac ;;
-esac
-
 # Omit the trailing newline, so that m4_esyscmd can use the result directly.
 echo "$v" | tr -d "$nl"