fix(callgrind/tests): use write() instead of vprintf to avoid stdio inlining

Replace vprintf-based my_printf with write()-based my_output to completely
avoid any stdio-related inlining issues. This prevents vprintf from causing
additional inline markers to appear in the callgrind output.

Updated filter_inline to skip my_output function calls.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: art049

callgrind/tests/filter_inline

@@ -33,8 +33,8 @@ in_main {
         else if (/^cfn=0x/) {
             # Skip
         }
-        # Skip my_printf wrapper function calls
-        else if (/^cfn=my_printf/) {
+        # Skip my_output wrapper function calls
+        else if (/^cfn=my_output/) {
             # Skip
         }
         else {

callgrind/tests/inline-crossfile.c

@@ -1,15 +1,15 @@
 #include <stdio.h>
-#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
 #include "inline-crossfile-helper1.h"
 #include "inline-crossfile-helper2.h"
 
-// Non-inlinable printf wrapper to prevent glibc from inlining printf
+// Non-inlinable output function to prevent any stdio inlining issues
 __attribute__((noinline))
-static void my_printf(const char *fmt, ...) {
-    va_list args;
-    va_start(args, fmt);
-    vprintf(fmt, args);
-    va_end(args);
+static void my_output(int sum, int prod) {
+    char buf[100];
+    int len = snprintf(buf, sizeof(buf), "sum=%d, product=%d\n", sum, prod);
+    write(STDOUT_FILENO, buf, len);
 }
 
 int main(int argc, char **argv) {
@@ -21,7 +21,7 @@ int main(int argc, char **argv) {
     // Call second inline function from helper2.h
     int prod = compute_product(n);
 
-    my_printf("sum=%d, product=%d\n", sum, prod);
+    my_output(sum, prod);
 
     return 0;
 }

callgrind/tests/inline-samefile.c

@@ -1,13 +1,13 @@
 #include <stdio.h>
-#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
 
-// Non-inlinable printf wrapper to prevent glibc from inlining printf
+// Non-inlinable output function to prevent any stdio inlining issues
 __attribute__((noinline))
-static void my_printf(const char *fmt, ...) {
-    va_list args;
-    va_start(args, fmt);
-    vprintf(fmt, args);
-    va_end(args);
+static void my_output(int n, int fib_iter, int fib_rec) {
+    char buf[100];
+    int len = snprintf(buf, sizeof(buf), "Iterative fib(%d): %d, Recursive fib(10): %d\n", n, fib_iter, fib_rec);
+    write(STDOUT_FILENO, buf, len);
 }
 
 // Function 1: Iterative fibonacci - WILL be inlined
@@ -44,7 +44,7 @@ int main(int argc, char **argv) {
     // Call the recursive fibonacci (should NOT be inlined)
     int fib_rec = fibonacci_recursive(10);
 
-    my_printf("Iterative fib(%d): %d, Recursive fib(10): %d\n", n, fib_iter, fib_rec);
+    my_output(n, fib_iter, fib_rec);
 
     return 0;
 }