[PATCH] fix -Wsign-conversion warning with gcc 8.2

[Sinan Kaya]

# HG changeset patch
# User Sinan Kaya <sinan.kaya at microsoft.com>
# Date 1647289518 14400
#      Mon Mar 14 16:25:18 2022 -0400
# Node ID f22520b612969dbfa17205129510927519370000
# Parent  a736a7a613ea6e182ff86fbadcb98bb0f8891c0b
fix -Wsign-conversion warning with gcc 8.2

Getting compiler warning with -Wsign-conversion.

/usr/include/nginx/core/ngx_crc32.h:31:47: warning: conversion to 
'uint32_t' {aka 'unsigned int'} from 'int' may change the sign of the 
result [-Wsign-conversion]
    31 |         crc = ngx_crc32_table_short[(crc ^ (c >> 4)) & 0xf] ^ 
(crc >> 4);

diff -r a736a7a613ea -r f22520b61296 src/core/ngx_crc32.h
--- a/src/core/ngx_crc32.h	Tue Feb 08 17:35:27 2022 +0300
+++ b/src/core/ngx_crc32.h	Mon Mar 14 16:25:18 2022 -0400
@@ -28,7 +28,8 @@
      while (len--) {
          c = *p++;
          crc = ngx_crc32_table_short[(crc ^ (c & 0xf)) & 0xf] ^ (crc >> 4);
-        crc = ngx_crc32_table_short[(crc ^ (c >> 4)) & 0xf] ^ (crc >> 4);
+        crc = ngx_crc32_table_short[(crc ^ (u_char)(c >> 4)) & 0xf];
+        crc = crc ^ (crc >> 4);
      }

      return crc ^ 0xffffffff;