build: Move PACKAGE_RELEASE definition from dpkg.h to configure.ac

There's no need to expose this macro in the API header. More so when the
PACKAGE_VERSION macro is only defined in config.h which is not installed
by default on the system.

configure.ac

@@ -123,6 +123,8 @@ DPKG_COMPILER_WARNINGS
 DPKG_COMPILER_OPTIMISATIONS
 DPKG_LINKER_OPTIMISATIONS
 DPKG_ARCHITECTURE
+AC_DEFINE([PACKAGE_RELEASE], [PACKAGE_VERSION " (" ARCHITECTURE ")"],
+          [Define the project release information, version and architecture])
 
 AC_CONFIG_FILES([ Makefile
 		  dpkg-deb/Makefile

lib/dpkg/dpkg.h

@@ -56,8 +56,6 @@ DPKG_BEGIN_DECLS
 #define REMOVECONFFEXTS    "~", ".bak", "%", \
                            DPKGTEMPEXT, DPKGNEWEXT, DPKGOLDEXT, DPKGDISTEXT
 
-#define PACKAGE_RELEASE    PACKAGE_VERSION " (" ARCHITECTURE ")"
-
 #define NEWCONFFILEFLAG    "newconffile"
 #define NONEXISTENTFLAG    "nonexistent"
 #define EMPTYHASHFLAG      "-"