SERVER-20664 Pull in zlib -Wshift-negative-value fixes

This is just cherry picking the following two commits from the zlib repo:

https://github.com/madler/zlib/commit/e54e1299404101a5a9d0cf5e45512b543967f958

Avoid shifts of negative values inflateMark().

The C standard says that bit shifts of negative integers is
undefined.  This casts to unsigned values to assure a known
result.

-------

https://github.com/madler/zlib/commit/44ae761dc2047038dc42a7e5a162d042fc392d2b

Clean up portability for shifts and integer sizes.

3 files changed, 7 insertions, 6 deletions

diff --git a/src/third_party/zlib-1.2.8/adler32.c b/src/third_party/zlib-1.2.8/adler32.c
index a868f073d8a..cfacc88cde3 100644
--- a/src/third_party/zlib-1.2.8/adler32.c
+++ b/src/third_party/zlib-1.2.8/adler32.c
@@ -11,7 +11,7 @@
 
 local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2));
 
-#define BASE 65521      /* largest prime smaller than 65536 */
+#define BASE 65521U     /* largest prime smaller than 65536 */
 #define NMAX 5552
 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
 
@@ -156,7 +156,7 @@ local uLong adler32_combine_(adler1, adler2, len2)
     sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;
     if (sum1 >= BASE) sum1 -= BASE;
     if (sum1 >= BASE) sum1 -= BASE;
-    if (sum2 >= (BASE << 1)) sum2 -= (BASE << 1);
+    if (sum2 >= ((unsigned long)BASE << 1)) sum2 -= ((unsigned long)BASE << 1);
     if (sum2 >= BASE) sum2 -= BASE;
     return sum1 | (sum2 << 16);
 }
diff --git a/src/third_party/zlib-1.2.8/inflate.c b/src/third_party/zlib-1.2.8/inflate.c
index 870f89bb4d3..83f5e044f04 100644
--- a/src/third_party/zlib-1.2.8/inflate.c
+++ b/src/third_party/zlib-1.2.8/inflate.c
@@ -243,7 +243,7 @@ int value;
     }
     if (bits > 16 || state->bits + bits > 32) return Z_STREAM_ERROR;
     value &= (1L << bits) - 1;
-    state->hold += value << state->bits;
+    state->hold += (unsigned)value << state->bits;
     state->bits += bits;
     return Z_OK;
 }
@@ -1504,9 +1504,10 @@ z_streamp strm;
 {
     struct inflate_state FAR *state;
 
-    if (strm == Z_NULL || strm->state == Z_NULL) return -1L << 16;
+    if (strm == Z_NULL || strm->state == Z_NULL)
+        return (long)(((unsigned long)0 - 1) << 16);
     state = (struct inflate_state FAR *)strm->state;
-    return ((long)(state->back) << 16) +
+    return (long)(((unsigned long)((long)state->back)) << 16) +
         (state->mode == COPY ? state->length :
             (state->mode == MATCH ? state->was - state->length : 0));
 }
diff --git a/src/third_party/zlib-1.2.8/zlib.h b/src/third_party/zlib-1.2.8/zlib.h
index 3e0c7672ac5..93efb6984cc 100644
--- a/src/third_party/zlib-1.2.8/zlib.h
+++ b/src/third_party/zlib-1.2.8/zlib.h
@@ -956,7 +956,7 @@ ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
    location in the input stream can be determined from avail_in and data_type
    as noted in the description for the Z_BLOCK flush parameter for inflate.
 
-     inflateMark returns the value noted above or -1 << 16 if the provided
+     inflateMark returns the value noted above or -65536 if the provided
    source stream state was inconsistent.
 */