Problem: ABI is not correct for 4.3.0

Solution: bump it to 5.2.0 as new stable APIs have been added

CMakeLists.txt

@@ -1074,7 +1074,7 @@ else()
     set_target_properties(libzmq PROPERTIES
       COMPILE_DEFINITIONS "DLL_EXPORT"
       PUBLIC_HEADER "${public_headers}"
-      VERSION "5.1.6"
+      VERSION "5.2.0"
       SOVERSION "5"
       OUTPUT_NAME "zmq"
       PREFIX "lib")

configure.ac

@@ -46,7 +46,7 @@ AC_SUBST(PACKAGE_VERSION)
 # ZeroMQ version 4.3.0: 6:6:1 (ABI version 5)
 #
 # libzmq -version-info current:revision:age
-LTVER="6:6:1"
+LTVER="7:0:2"
 AC_SUBST(LTVER)
 
 # Take a copy of original flags