Fixes mpaland#137: Use strict C prototypes

* Now using `func_name(void)` instead of `func_name()` in declarations, wherever relevant
* Now checking for strict prototypes when compiling C test programs

Author: eyalroz

test/CMakeLists.txt

@@ -71,6 +71,9 @@ foreach(tgt ${test_targets})
 			-fverbose-asm
 			-Wunused-parameter
 		)
+		target_compile_options(${tgt} PRIVATE
+		  "$<$<COMPILE_LANGUAGE:C>:-Wstrict-prototypes>"
+		)			
 		if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
 			target_compile_options(${tgt} PRIVATE -ffat-lto-objects)
 		endif()

test/aliasing.c

@@ -25,14 +25,14 @@ void putchar_(char c)
   }
 }
 
-void clear_buffer()
+void clear_buffer(void)
 {
   for(int i = 0; i < BufferSize; i++) {
     buffer[i] = '\0';
   }
 }
 
-int main()
+int main(void)
 {
 #if PRINTF_ALIAS_STANDARD_FUNCTION_NAMES
   clear_buffer();