[libpng16] Use --zprefix in oss-fuzz libpng build to avoid conflict with system libz.
diff --git a/ANNOUNCE b/ANNOUNCE
index f2d9853..5c339e2 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.35beta01 - October 1, 2017
+Libpng 1.6.35beta01 - October 3, 2017
 
 This is not intended to be a public release. It will be replaced
 within a few weeks by a public version or by another test version.
@@ -24,10 +24,11 @@
 
 Changes since the last public release (1.6.34):
 
-Version 1.6.35beta01 [October 1, 2017]
+Version 1.6.35beta01 [October 3, 2017]
   Restored 21 of the contrib/pngsuite/i*.png, which do not cause test
     failures. Placed the remainder in contrib/pngsuite/interlaced/i*.png.
   Clone zlib into the oss-fuzz zlib project and build zlib alongside libpng.
+  Use --zprefix in oss-fuzz libpng build to avoid conflict with system libz.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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diff --git a/CHANGES b/CHANGES
index eaaef6f..e1037ae 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6040,10 +6040,11 @@
 Version 1.6.34 [September 29, 2017]
   Removed contrib/pngsuite/i*.png; some of caused test failures.
 
-Version 1.6.35beta01 [October 1, 2017]
+Version 1.6.35beta01 [October 3, 2017]
   Restored 21 of the contrib/pngsuite/i*.png, which do not cause test
     failures. Placed the remainder in contrib/pngsuite/interlaced/i*.png.
   Clone zlib into the oss-fuzz zlib project and build zlib alongside libpng.
+  Use --zprefix in oss-fuzz libpng build to avoid conflict with system libz.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/contrib/oss-fuzz/build.sh b/contrib/oss-fuzz/build.sh
index 300a7e8..1ddd150 100755
--- a/contrib/oss-fuzz/build.sh
+++ b/contrib/oss-fuzz/build.sh
@@ -14,7 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-# Last changed in libpng 1.6.35 [October 1, 2017]
+# Last changed in libpng 1.6.35 [October 3, 2017]
 #
 # Revisions by Glenn Randers-Pehrson, 2017:
 # 1. Build only the library, not the tools (changed "make -j$(nproc) all" to
@@ -32,7 +32,7 @@
 mv scripts/pnglibconf.dfa.temp scripts/pnglibconf.dfa
 
 # build zlib library.
-(cd ../zlib; ./configure; make -j$(nproc) clean; make -j$(nproc) all)
+(cd ../zlib; ./configure --zprefix; make -j$(nproc) clean; make -j$(nproc) all)
 
 # build the libpng library.
 autoreconf -f -i