clar: use size_t to keep track of current line number

We use the `__LINE__` macro in several places throughout clar to allow
easier traceability when e.g. a test fails. While `__LINE__` is of type
`size_t`, the clar functions all accept an integer and thus may loose
precision. While unlikely that any file in our codebase will exceed a
linecount of `INT_MAX`, let's convert it anyway to silence any compiler
warnings.

tests/clar.c

@@ -96,7 +96,7 @@ fixture_path(const char *base, const char *fixture_name);
 
 struct clar_error {
 	const char *file;
-	int line_number;
+	size_t line_number;
 	const char *error_msg;
 	char *description;
 
@@ -589,7 +589,7 @@ void clar__skip(void)
 
 void clar__fail(
 	const char *file,
-	int line,
+	size_t line,
 	const char *error_msg,
 	const char *description,
 	int should_abort)
@@ -621,7 +621,7 @@ void clar__fail(
 void clar__assert(
 	int condition,
 	const char *file,
-	int line,
+	size_t line,
 	const char *error_msg,
 	const char *description,
 	int should_abort)
@@ -634,7 +634,7 @@ void clar__assert(
 
 void clar__assert_equal(
 	const char *file,
-	int line,
+	size_t line,
 	const char *err,
 	int should_abort,
 	const char *fmt,

tests/clar.h

@@ -141,22 +141,22 @@ void clar__skip(void);
 
 void clar__fail(
 	const char *file,
-	int line,
+	size_t line,
 	const char *error,
 	const char *description,
 	int should_abort);
 
 void clar__assert(
 	int condition,
 	const char *file,
-	int line,
+	size_t line,
 	const char *error,
 	const char *description,
 	int should_abort);
 
 void clar__assert_equal(
 	const char *file,
-	int line,
+	size_t line,
 	const char *err,
 	int should_abort,
 	const char *fmt,

tests/clar/print.h

@@ -20,7 +20,7 @@ static void clar_print_error(int num, const struct clar_report *report, const st
 {
 	printf("  %d) Failure:\n", num);
 
-	printf("%s::%s [%s:%d]\n",
+	printf("%s::%s [%s:%"PRIuZ"]\n",
 		report->suite,
 		report->test,
 		error->file,