make newlib the default

Author: rgrr

cmake/preload/toolchains/util/pico_arm_clang_common.cmake

@@ -44,8 +44,11 @@ endforeach()
 list(APPEND CMAKE_TRY_COMPILE_PLATFORM_VARIABLES PICO_CLIB)
 
 set(_PICO_CLIB_PATH "${PICO_COMPILER_DIR}/../lib/clang-runtimes/arm-none-eabi")
-if(PICO_CLIB STREQUAL "")
-    # use default from above
+if(PICO_CLIB STREQUAL ""  OR  PICO_CLIB STREQUAL "newlib")
+    # newlib is 1st class choice
+    if(EXISTS "${PICO_COMPILER_DIR}/../lib/clang-runtimes/newlib/arm-none-eabi")
+        set(_PICO_CLIB_PATH "${PICO_COMPILER_DIR}/../lib/clang-runtimes/newlib/arm-none-eabi")
+    endif()
 elseif(PICO_CLIB STREQUAL "llvm_libc")
     if(EXISTS "${PICO_COMPILER_DIR}/../lib/clang-runtimes/llvmlibc/arm-none-eabi")
         set(_PICO_CLIB_PATH "${PICO_COMPILER_DIR}/../lib/clang-runtimes/llvmlibc/arm-none-eabi")
@@ -54,10 +57,6 @@ elseif(PICO_CLIB STREQUAL "picolibc")
     if(EXISTS "${PICO_COMPILER_DIR}/../lib/clang-runtimes/picolibc/arm-none-eabi")
         set(_PICO_CLIB_PATH "${PICO_COMPILER_DIR}/../lib/clang-runtimes/picolibc/arm-none-eabi")
     endif()
-elseif(PICO_CLIB STREQUAL "newlib")
-    if(EXISTS "${PICO_COMPILER_DIR}/../lib/clang-runtimes/newlib/arm-none-eabi")
-        set(_PICO_CLIB_PATH "${PICO_COMPILER_DIR}/../lib/clang-runtimes/newlib/arm-none-eabi")
-    endif()
 else()
     message(FATAL_ERROR "PICO_CLIB must be one of newlib, picolib, llvm_libc or empty (but is '${PICO_CLIB}')")
 endif()