cmake: add -rdynamic flag to fix "undefined symbol" issue starting from ubuntu 26.04

This would happen when loading plugin .so.
This was likely the default before, or it is needed now because of more
aggresive linking optimizations.
Either way, according to the docs, it should be used when dealing with
exactly this use-case.

Author: sedmicha

CMakeLists.txt

@@ -65,10 +65,10 @@ option(PACKAGE_BUILDER_DEB   "Enable DEB package builder (make deb)"    OFF)
 
 ## -----------------------------------------------------------------------------
 # Hard coded definitions
-set(CMAKE_C_FLAGS            "${CMAKE_C_FLAGS} -fvisibility=hidden -std=gnu11")
+set(CMAKE_C_FLAGS            "${CMAKE_C_FLAGS} -fvisibility=hidden -std=gnu11 -rdynamic")
 set(CMAKE_C_FLAGS_RELEASE    "-O2 -DNDEBUG")
 set(CMAKE_C_FLAGS_DEBUG      "-g -O0 -Wall -Wextra -pedantic")
-set(CMAKE_CXX_FLAGS          "${CMAKE_CXX_FLAGS} -fvisibility=hidden -std=gnu++11")
+set(CMAKE_CXX_FLAGS          "${CMAKE_CXX_FLAGS} -fvisibility=hidden -std=gnu++11 -rdynamic")
 set(CMAKE_CXX_FLAGS_RELEASE  "-O2 -DNDEBUG")
 set(CMAKE_CXX_FLAGS_DEBUG    "-g -O0 -Wall -Wextra -pedantic")