aws: macos: prevent buffer overflow on address sanitier

[cosmo0920]

This issue is reported by addrress sanitizer on macOS.
On Linux, this isue won't be happened.

Test flb_get_s3_key_invalid_key_length...       [2023/07/31 17:50:07] [ warn] [s3_key] Object key length is longer than the 1024 character limit.
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==67093==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x000109409580 at pc 0x000106924088 bp 0x00016b48e020 sp 0x00016b48d7e0
READ of size 1025 at 0x000109409580 thread T0
    #0 0x106924084 in wrap_strlen+0x164 (libclang_rt.asan_osx_dynamic.dylib:arm64e+0x18084) (BuildId: f0a7ac5c49bc3abc851181b6f92b308a32000000200000000100000000000b00)
    #1 0x1049899b0 in flb_get_s3_key flb_aws_util.c:923
    #2 0x10497fa18 in test_flb_get_s3_key_invalid_key_length aws_util.c:278
    #3 0x10497cbe8 in acutest_do_run_ acutest.h:1034
    #4 0x10497ab90 in acutest_run_ acutest.h:1130
    #5 0x1049779c8 in main acutest.h:1769
    #6 0x188db7f24  (<unknown module>)

0x000109409580 is located 0 bytes to the right of 1024-byte region [0x000109409180,0x000109409580)
allocated by thread T0 here:
    #0 0x10694f234 in wrap_calloc+0x9c (libclang_rt.asan_osx_dynamic.dylib:arm64e+0x43234) (BuildId: f0a7ac5c49bc3abc851181b6f92b308a32000000200000000100000000000b00)
    #1 0x104987270 in flb_calloc flb_mem.h:95
    #2 0x10498991c in flb_get_s3_key flb_aws_util.c:912
    #3 0x10497fa18 in test_flb_get_s3_key_invalid_key_length aws_util.c:278
    #4 0x10497cbe8 in acutest_do_run_ acutest.h:1034
    #5 0x10497ab90 in acutest_run_ acutest.h:1130
    #6 0x1049779c8 in main acutest.h:1769
    #7 0x188db7f24  (<unknown module>)

SUMMARY: AddressSanitizer: heap-buffer-overflow (libclang_rt.asan_osx_dynamic.dylib:arm64e+0x18084) (BuildId: f0a7ac5c49bc3abc851181b6f92b308a32000000200000000100000000000b00) in wrap_strlen+0x164
Shadow bytes around the buggy address:
  0x0070212a1260: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0070212a1270: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0070212a1280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0070212a1290: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0070212a12a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0070212a12b0:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0070212a12c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0070212a12d0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0070212a12e0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0070212a12f0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0070212a1300: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==67093==ABORTING
  Test interrupted by SIGABRT.

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