gen_arduino_files.cmake: fix Mac path normalization

TOP_DIR includes a trailing slash on Mac, but not on Linux. On Mac, the
path to the variant directory is generated with a double slash, and this
makes the 'iwithprefixbefore' replacement fail. A second NORMALIZE step
fixes this.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

Author: pillo79

extra/gen_arduino_files.cmake

@@ -21,7 +21,7 @@ foreach(variant ${VARIANTS})
 		continue()
 	endif()
 
-	cmake_path(SET dir ${TOP_DIR}/variants/${variant})
+	cmake_path(SET dir ${TOP_DIR}/variants/${variant} NORMALIZE)
 	if(NOT EXISTS ${dir}/llext-edk/cmake.cflags)
 		continue()
 	endif()