add PLATFORM_RP2040 cmake variable

Author: sberkun

core/CMakeLists.txt

@@ -93,7 +93,7 @@ endif()
 
 # Link with thread library, unless we are on the Zephyr platform.
 if(NOT DEFINED LF_SINGLE_THREADED OR DEFINED LF_TRACE)
-    if (NOT (PLATFORM_ZEPHYR OR ${CMAKE_SYSTEM_NAME} STREQUAL "Rp2040"))
+    if (NOT (PLATFORM_ZEPHYR OR PLATFORM_RP2040))
         find_package(Threads REQUIRED)
         target_link_libraries(reactor-c PUBLIC Threads::Threads)
     endif()

core/platform/CMakeLists.txt

@@ -24,6 +24,7 @@ elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Zephyr")
     set(PLATFORM_ZEPHYR true)
 elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Rp2040")
     list(APPEND CORE_COMPILE_DEFS PLATFORM_RP2040)
+    set(PLATFORM_RP2040 true)
 endif()
 
 # Prepend all sources with platform