Sync zlib sources with GCC, upgrading to 1.2.10.

Changes in 1.2.10 (2 Jan 2017)
- Avoid warnings on snprintf() return value
- Fix bug in deflate_stored() for zero-length input
- Fix bug in gzwrite.c that produced corrupt gzip files
- Remove files to be installed before copying them in Makefile.in
- Add warnings when compiling with assembler code

Changes in 1.2.9 (31 Dec 2016)
- Fix contrib/minizip to permit unzipping with desktop API [Zouzou]
- Improve contrib/blast to return unused bytes
- Assure that gzoffset() is correct when appending
- Improve compress() and uncompress() to support large lengths
- Fix bug in test/example.c where error code not saved
- Remedy Coverity warning [Randers-Pehrson]
- Improve speed of gzprintf() in transparent mode
- Fix inflateInit2() bug when windowBits is 16 or 32
- Change DEBUG macro to ZLIB_DEBUG
- Avoid uninitialized access by gzclose_w()
- Allow building zlib outside of the source directory
- Fix bug that accepted invalid zlib header when windowBits is zero
- Fix gzseek() problem on MinGW due to buggy _lseeki64 there
- Loop on write() calls in gzwrite.c in case of non-blocking I/O
- Add --warn (-w) option to ./configure for more compiler warnings
- Reject a window size of 256 bytes if not using the zlib wrapper
- Fix bug when level 0 used with Z_HUFFMAN or Z_RLE
- Add --debug (-d) option to ./configure to define ZLIB_DEBUG
- Fix bugs in creating a very large gzip header
- Add uncompress2() function, which returns the input size used
- Assure that deflateParams() will not switch functions mid-block
- Dramatically speed up deflation for level 0 (storing)
- Add gzfread(), duplicating the interface of fread()
- Add gzfwrite(), duplicating the interface of fwrite()
- Add deflateGetDictionary() function
- Use snprintf() for later versions of Microsoft C
- Fix *Init macros to use z_ prefix when requested
- Replace as400 with os400 for OS/400 support [Monnerat]
- Add crc32_z() and adler32_z() functions with size_t lengths
- Update Visual Studio project files [AraHaan]

zlib/old/Makefile.emx

@@ -11,7 +11,7 @@ CC=gcc -Zwin32
 
 #CFLAGS=-MMD -O
 #CFLAGS=-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7
-#CFLAGS=-MMD -g -DDEBUG
+#CFLAGS=-MMD -g -DZLIB_DEBUG
 CFLAGS=-MMD -O3 $(BUTT) -Wall -Wwrite-strings -Wpointer-arith -Wconversion \
              -Wstrict-prototypes -Wmissing-prototypes
 

zlib/old/os2/Makefile.os2

@@ -14,7 +14,7 @@ CC=gcc -Zomf -s
 
 CFLAGS=-O6 -Wall
 #CFLAGS=-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7
-#CFLAGS=-g -DDEBUG
+#CFLAGS=-g -DZLIB_DEBUG
 #CFLAGS=-O3 -Wall -Wwrite-strings -Wpointer-arith -Wconversion \
 #           -Wstrict-prototypes -Wmissing-prototypes