bpftool: Remove usage of reallocarray()

This commit fixes a compilation error on systems with glibc < 2.26 [0]:

```
In file included from main.h:14:0,
                 from gen.c:24:
linux/tools/include/tools/libc_compat.h:11:21: error: attempt to use poisoned "reallocarray"
 static inline void *reallocarray(void *ptr, size_t nmemb, size_t size)
```

This happens because gen.c pulls <bpf/libbpf_internal.h>, and then
<tools/libc_compat.h> (through main.h). When
COMPAT_NEED_REALLOCARRAY is set, libc_compat.h defines reallocarray()
which libbpf_internal.h poisons with a GCC pragma.

This commit reuses libbpf_reallocarray() implemented in commit
029258d7b228 ("libbpf: Remove any use of reallocarray() in libbpf").

v1 -> v2:
- reuse libbpf_reallocarray() instead of reimplementing it

Fixes: a9caaba399f9 ("bpftool: Implement "gen min_core_btf" logic")
Reported-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220221125617.39610-1-mauricio@kinvolk.io

[0]: https://lore.kernel.org/bpf/3bf2bd49-9f2d-a2df-5536-bc0dde70a83b@isovalent.com/

1 files changed, 1 insertions, 1 deletions

diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 0c3840596b5a..0468e5b24bd4 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -8,10 +8,10 @@
 #undef GCC_VERSION
 #include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <linux/bpf.h>
 #include <linux/compiler.h>
 #include <linux/kernel.h>
-#include <tools/libc_compat.h>
 
 #include <bpf/hashmap.h>
 #include <bpf/libbpf.h>