Use hex character constants for char values
Avoids "warning: implicit conversion from 'int' to 'const char'
changes value [from 139 to -117 etc]" with recent Clang.
@@ -125,11 +125,11 @@ const char BAM_DNA_DEL = '-';
const char BAM_DNA_PAD = '*';
// zlib & BGZF constants
-const char GZIP_ID1 = 31;
-const char GZIP_ID2 = 139;
+const char GZIP_ID1 = '\x1F';
+const char GZIP_ID2 = '\x8B';
const char CM_DEFLATE = 8;
const char FLG_FEXTRA = 4;
-const char OS_UNKNOWN = 255;
+const char OS_UNKNOWN = '\xFF';
const char BGZF_XLEN = 6;
const char BGZF_ID1 = 66;
const char BGZF_ID2 = 67;
