eal/windows: fix debug build with MinGW

Compiling with MinGW in --buildtype=debug produces a redefinition
error for strncasecmp.

The root cause is that rte_os.h shouldn't be injecting POSIX definitions
into the environment.  It is the applications responsibility to decide
how to handle missing functionality.

Resolving this properly will require further work, but in the meantime
wrap all such definitions with #ifndef/#endif.  This resolves the specific
issue with strncasecmp and handles similar issues that applications may
encounter.

Fixes: e8428a9d89 ("eal/windows: add some basic functions and macros")
Cc: stable@dpdk.org

Reported-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Nick Connolly <nick.connolly@mayadata.io>

lib/librte_eal/windows/include/rte_os.h

@@ -25,22 +25,42 @@ extern "C" {
 #define PATH_MAX _MAX_PATH
 #endif
 
+#ifndef sleep
 #define sleep(x) Sleep(1000 * (x))
+#endif
 
+#ifndef strerror_r
 #define strerror_r(a, b, c) strerror_s(b, c, a)
+#endif
 
+#ifndef strdup
 /* strdup is deprecated in Microsoft libc and _strdup is preferred */
 #define strdup(str) _strdup(str)
+#endif
 
+#ifndef strtok_r
 #define strtok_r(str, delim, saveptr) strtok_s(str, delim, saveptr)
+#endif
 
+#ifndef index
 #define index(a, b)     strchr(a, b)
+#endif
+
+#ifndef rindex
 #define rindex(a, b)    strrchr(a, b)
+#endif
 
+#ifndef strncasecmp
 #define strncasecmp(s1, s2, count)        _strnicmp(s1, s2, count)
+#endif
 
+#ifndef close
 #define close _close
+#endif
+
+#ifndef unlink
 #define unlink _unlink
+#endif
 
 /* cpu_set macros implementation */
 #define RTE_CPU_AND(dst, src1, src2) CPU_AND(dst, src1, src2)
@@ -89,7 +109,9 @@ eal_strerror(int code)
 	return buffer;
 }
 
+#ifndef strerror
 #define strerror eal_strerror
+#endif
 
 #endif /* RTE_TOOLCHAIN_GCC */