From: Ole Streicher <olebole@debian.org>
Date: Thu, 22 Dec 2016 14:24:44 +0100
Subject: Remove unneeded prototype declaration for strdup().

strdup is already defined in `string.h`.  Since strdup may be a macro,
the additional declaration lead to the following error message under
Debian:

```
make[4]: Entering directory '/build/montage-5.0+dfsg/lib/src/coord'
gcc -g -O2 -fdebug-prefix-map=/build/montage-5.0+dfsg=. -fstack-protector-strong
In file included from /usr/include/string.h:630:0,
                 from ccalc.c:5:
ccalc.c:28:7: error: expected identifier or '(' before '__extension__'
 char *strdup(const char *s1);
       ^
<builtin>: recipe for target 'ccalc.o' failed
make[4]: *** [ccalc.o] Error 1
```

---
 grid/Pegasus/hashtable.c | 2 --
 lib/src/coord/ccalc.c    | 1 -
 2 files changed, 3 deletions(-)

diff --git a/grid/Pegasus/hashtable.c b/grid/Pegasus/hashtable.c
index 760cdfe..693bc4c 100644
--- a/grid/Pegasus/hashtable.c
+++ b/grid/Pegasus/hashtable.c
@@ -4,8 +4,6 @@
 
 #include <hashtable.h>
 
-char *strdup(const char *s1);
-
 int HT_debug = 0;
 
 /********************************************************/
diff --git a/lib/src/coord/ccalc.c b/lib/src/coord/ccalc.c
index 472aa2c..b3679b9 100644
--- a/lib/src/coord/ccalc.c
+++ b/lib/src/coord/ccalc.c
@@ -25,7 +25,6 @@ static int ConverttoDD(char *fmt, char *clon, char *clat, double *lon,
 static int ConvertfromDD(char *fmt, char *clongprec, char *clatprec, 
 			 char *clon, char *clat, double *lon, double *lat);
 static char *downcase(char *s);
-char *strdup(const char *s1);
 int ParseUnits(char *cunit, int *chflag, CoordUnit *unit);
 int ParsePrec(CoordUnit units, char *cprec, int longflag);
 
