cmake/re-config: add default CMAKE_BUILD_TYPE and fix RELEASE definition

Empty CMAKE_BUILD_TYPE is not equal to Debug build and can lead to
missing debug symbols. Since cmake also non build configurations it's
better to set RELEASE definition by CONFIG generator expression.

cmake/re-config.cmake

@@ -18,6 +18,12 @@ option(USE_OPENSSL "Enable OpenSSL" ${OPENSSL_FOUND})
 option(USE_UNIXSOCK "Enable Unix Domain Sockets" ON)
 option(USE_TRACE "Enable Tracing helpers" OFF)
 
+if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+    message(STATUS "Setting build type to 'Debug' as none was specified.")
+    set(CMAKE_BUILD_TYPE "Debug" CACHE STRING "Choose the type of build."
+        FORCE)
+endif()
+
 check_symbol_exists("arc4random" "stdlib.h" HAVE_ARC4RANDOM)
 if(HAVE_ARC4RANDOM)
   list(APPEND RE_DEFINITIONS -DHAVE_ARC4RANDOM)
@@ -178,11 +184,10 @@ endif()
 list(APPEND RE_DEFINITIONS
   -DARCH="${CMAKE_SYSTEM_PROCESSOR}"
   -DOS="${CMAKE_SYSTEM_NAME}"
+  $<$<NOT:$<CONFIG:DEBUG>>:-DRELEASE>
 )
 
-if(${CMAKE_BUILD_TYPE} MATCHES "[Rr]el")
-  list(APPEND RE_DEFINITIONS -DRELEASE)
-else()
+if(NOT ${CMAKE_BUILD_TYPE} MATCHES "[Rr]el")
   if(Backtrace_FOUND)
     set(CMAKE_ENABLE_EXPORTS ON)
   endif()