[BOLT][TEST] Fix test failures on AArch64 builder

Address X86 tests failures on AArch64 builder:
https://lab.llvm.org/staging/#/builders/211/builds/82

Inputs fail to cross-compile due to a missing header:
```
/usr/include/stdio.h:27:10: fatal error: 'bits/libc-header-start.h' file not found
#include <bits/libc-header-start.h>
```

As inputs are linked with `-nostdlib` anyway, don't include stdio.h.

Reviewed By: yota9

Differential Revision: https://reviews.llvm.org/D124863

bolt/test/Inputs/icf-jump-tables.c

@@ -1,5 +1,3 @@
-#include <stdio.h>
-
 int inc(int x) {
   switch (x) {
     case 0: puts("0"); return 1;

bolt/test/X86/Inputs/avx512.c

@@ -1,14 +1,9 @@
-#include <stdio.h>
-
 void use_avx512() {
-  printf("after first entry\n");
   asm (".byte 0x62, 0xe2, 0xf5, 0x70, 0x2c, 0xda");
-  asm ("secondary_entry:");
-  printf("after secondary entry\n");
+  asm("secondary_entry:");
 }
 
 int main() {
-  printf("about to use avx-512 instruction...\n");
   use_avx512();
 
   return 0;

bolt/test/X86/Inputs/inline-foo.c

@@ -1,4 +1,4 @@
-#include <stdio.h>
+// don't include stdio as the test is linked with -nostdlib
 
 void foo() {
   puts("Hello world!\n");