Everywhere: Name debug macros more consistently.

Personally, I prefer the naming convention DEBUG_FOO over FOO_DEBUG, but
the majority of the debug macros are already named in the latter naming
convention, so I just enforce consistency here.

This was done with the following script:

    find . \( -name '*.cpp' -o -name '*.h' -o -name '*.in' \) -not -path './Toolchain/*' -not -path './Build/*' -exec sed -i -E 's/DEBUG_PATH/PATH_DEBUG/' {} \;

Userland/Libraries/LibCore/Gzip.cpp

@@ -52,7 +52,7 @@ static Optional<ByteBuffer> get_gzip_payload(const ByteBuffer& data)
         return data[current++];
     };
 
-#if DEBUG_GZIP
+#if GZIP_DEBUG
     dbgln("get_gzip_payload: Skipping over gzip header.");
 #endif
 
@@ -135,7 +135,7 @@ Optional<ByteBuffer> Gzip::decompress(const ByteBuffer& data)
             source.data(), &source_len);
 
         if (puff_ret == 0) {
-#if DEBUG_GZIP
+#if GZIP_DEBUG
             dbgln("Gzip::decompress: Decompression success.");
 #endif
             destination.trim(destination_len);
@@ -144,7 +144,7 @@ Optional<ByteBuffer> Gzip::decompress(const ByteBuffer& data)
 
         if (puff_ret == 1) {
             // FIXME: Find a better way of decompressing without needing to try over and over again.
-#if DEBUG_GZIP
+#if GZIP_DEBUG
             dbgln("Gzip::decompress: Output buffer exhausted. Growing.");
 #endif
             destination.grow(destination.size() * 2);