[master] b7375650e build: Add a PACKAGE_BRANCH substitution

[Dridi Boukelmoune]

commit b7375650e9e7a665ca2870e8e852f3f993a1524c
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Tue Jul 26 09:42:28 2022 +0200

    build: Add a PACKAGE_BRANCH substitution
    
    It works both with trunk or x.y.z versions, resulting in trunk for the
    former and x.y for the latter.

diff --git a/configure.ac b/configure.ac
index b8175d4d6..ca2bf0b01 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,6 +9,11 @@ AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_USE_SYSTEM_EXTENSIONS
 
+PACKAGE_BRANCH=${PACKAGE_VERSION%.*}
+AC_SUBST([PACKAGE_BRANCH])
+AC_DEFINE_UNQUOTED([PACKAGE_BRANCH], ["$PACKAGE_BRANCH"],
+	[Define the branch of this package.])
+
 # save command line CFLAGS for use in VCC_CC (to pass through things like -m64)
 # and make distcheck configure
 OCFLAGS="$CFLAGS"