[libpng16] The macros passed in the command line to Borland make were ignored if

similarly-named macros were already defined in makefiles. This behavior
is different from POSIX make and other make programs.  Surround the
macro definitions with ifndef guards (Cosmin).
diff --git a/ANNOUNCE b/ANNOUNCE
index d7d9dac..7ab54fc 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.15rc01 - November 13, 2014
+Libpng 1.6.15rc02 - November 14, 2014
 
 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.
@@ -8,20 +8,20 @@
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   1.6.15rc01.tar.xz (LZMA-compressed, recommended)
-   1.6.15rc01.tar.gz
+   1.6.15rc02.tar.xz (LZMA-compressed, recommended)
+   1.6.15rc02.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lp1615r01.7z  (LZMA-compressed, recommended)
-   lp1615r01.zip
+   lp1615r02.7z  (LZMA-compressed, recommended)
+   lp1615r02.zip
 
 Other information:
 
-   1.6.15rc01-README.txt
-   1.6.15rc01-LICENSE.txt
-   libpng-1.6.15rc01-*.asc (armored detached GPG signatures)
+   1.6.15rc02-README.txt
+   1.6.15rc02-LICENSE.txt
+   libpng-1.6.15rc02-*.asc (armored detached GPG signatures)
 
 Changes since the last public release (1.6.14):
 
@@ -78,6 +78,12 @@
 
 Version 1.6.15rc01 [November 13, 2014]
 
+Version 1.6.15rc02 [November 14, 2014]
+  The macros passed in the command line to Borland make are ignored if
+    similarly-named macros are already defined in makefiles. This behavior
+    is different from POSIX make and other make programs.  Surround the
+    macro definitions with ifndef guards (Cosmin).
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
diff --git a/CHANGES b/CHANGES
index c7918a7..39c5ab7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5086,6 +5086,12 @@
 
 Version 1.6.15rc01 [November 13, 2014]
 
+Version 1.6.15rc02 [November 14, 2014]
+  The macros passed in the command line to Borland make are ignored if
+    similarly-named macros are already defined in makefiles. This behavior
+    is different from POSIX make and other make programs.  Surround the
+    macro definitions with ifndef guards (Cosmin).
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
diff --git a/scripts/makefile.bc32 b/scripts/makefile.bc32
index d488a54..bdbc4cb 100644
--- a/scripts/makefile.bc32
+++ b/scripts/makefile.bc32
@@ -52,7 +52,9 @@
 
 # Pre-built configuration
 # See scripts\pnglibconf.mak for more options
+!ifndef PNGLIBCONF_H_PREBUILT
 PNGLIBCONF_H_PREBUILT = scripts\pnglibconf.h.prebuilt
+!endif
 
 ## Variables
 OBJS = \
diff --git a/scripts/makefile.bor b/scripts/makefile.bor
index a01f738..6693772 100644
--- a/scripts/makefile.bor
+++ b/scripts/makefile.bor
@@ -60,7 +60,9 @@
 
 # Pre-built configuration
 # See scripts\pnglibconf.mak for more options
+!ifndef PNGLIBCONF_H_PREBUILT
 PNGLIBCONF_H_PREBUILT = scripts\pnglibconf.h.prebuilt
+!endif
 
 ## Variables
 
diff --git a/scripts/makefile.tc3 b/scripts/makefile.tc3
index c917a08..1d01502 100644
--- a/scripts/makefile.tc3
+++ b/scripts/makefile.tc3
@@ -16,7 +16,9 @@
 
 # Pre-built configuration
 # See scripts\pnglibconf.mak for more options
+!ifndef PNGLIBCONF_H_PREBUILT
 PNGLIBCONF_H_PREBUILT = scripts\pnglibconf.h.prebuilt
+!endif
 
 O=.obj
 E=.exe