Align kprint in os_mock with <kprint> header definition.

Clean up whitespace

Author: alfreb

src/plugins/field_medic/fieldmedic.cpp

@@ -108,7 +108,7 @@ void kernel::diag::post_service() noexcept {
   DIAGNOSE(invariant_post_init_libc(), "Post init libc invariant still holds");
 
   if (diag_failures == 0){
-    MYINFO("Diagnose complete. Healthy  ✅");
+    MYINFO("Diagnose complete. Healthy ✅");
   } else {
     MYINFO("Diagnose complete: %i / %i checks failed", diag_failures, (diag_failures + diag_successes));
   }

test/lest_util/os_mock.cpp

@@ -67,6 +67,7 @@ void Service::ready()
   printf("Service::ready() called\n");
 }
 
+__attribute__ ((format (printf, 1, 2)))
 extern "C"
 void kprintf(const char* format, ...)
 {
@@ -77,9 +78,9 @@ void kprintf(const char* format, ...)
 }
 
 extern "C"
-void kprint(char* str)
+void kprint(const char* str)
 {
-printf("%s", str);
+  printf("%s", str);
 }
 
 #include <os.hpp>
@@ -157,8 +158,8 @@ extern "C" {
     printf("<serial print1> %s\n", cstr);
   }
 
-  void __serial_print(const char* cstr, int len) {
-    printf("<serial print> %.*s", len, cstr);
+  void __serial_print(const char* cstr, size_t len) {
+    printf("<serial print> %.*s", static_cast<int>(len), cstr);
   }
 } // ~ extern "C"