Fix sources should be private for a library

CMakeLists.txt

@@ -7,7 +7,7 @@ project(pulp-nnx
 
 add_library(pulp-nnx STATIC)
 
-target_sources(pulp-nnx PUBLIC util/pulp_nnx_util.c util/hwpe.c)
+target_sources(pulp-nnx PRIVATE util/pulp_nnx_util.c util/hwpe.c)
 target_include_directories(pulp-nnx PUBLIC inc util)
 
 option(USE_NE16 "Use the NE16 accelerator.")
@@ -20,7 +20,7 @@ endif()
 if (${USE_NE16})
 	message(STATUS "[PULP-NNX] Using the NE16 accelerator.")
 	target_sources(pulp-nnx
-		PUBLIC
+		PRIVATE
 			ne16/bsp/ne16_pulp_bsp.c
 			ne16/hal/ne16.c
 			ne16/hal/ne16_task.c
@@ -37,7 +37,7 @@ endif()
 if (${USE_NEUREKA})
 	message(STATUS "[PULP-NNX] Using the N-EUREKA accelerator.")
 	target_sources(pulp-nnx
-		PUBLIC
+		PRIVATE
 			neureka/bsp/neureka_siracusa_bsp.c
 			neureka/hal/neureka.c
 			neureka/hal/neureka_task.c