Rename `DEBUG` to `DEBUG_SIPHASH`

`DEBUG` is too generic a name to use for a flag that causes SipHash to
log to the console on every hash operation; changed it to
`DEBUG_SIPHASH`.

An example: Xcode's project templates have a `-DDEBUG=1` Clang flag in
the 'Debug' config, so nearly every iOS and macOS app defines DEBUG
in dev builds! When I (@snej) added SipHash to my Mac project, I
started getting huge amounts of console logs until I found and renamed
its `#ifdef DEBUG`.

1 files changed, 1 insertions, 1 deletions

diff --git a/siphash.c b/siphash.c
index 003eb5b..8678e33 100644
--- a/siphash.c
+++ b/siphash.c
@@ -64,7 +64,7 @@
         v2 = ROTL(v2, 32);                                                     \
     } while (0)
 
-#ifdef DEBUG
+#ifdef DEBUG_SIPHASH
 #define TRACE                                                                  \
     do {                                                                       \
         printf("(%3zu) v0 %016" PRIx64 "\n", inlen, v0);                       \