picohttpparser: fix __SSE_4_2__ CPP check

This fixes a `-Wundef' warning with gcc, and `__SSE_4_2__' is a
defined-ness check everywhere else.

1 files changed, 1 insertions, 1 deletions

diff --git a/picohttpparser_c.h b/picohttpparser_c.h
index 0db7dcb..c5e345d 100644
--- a/picohttpparser_c.h
+++ b/picohttpparser_c.h
@@ -105,7 +105,7 @@ static const char *token_char_map = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
 static const char *findchar_fast(const char *buf, const char *buf_end, const char *ranges, size_t ranges_size, int *found)
 {
     *found = 0;
-#if __SSE4_2__
+#ifdef __SSE4_2__
     if (likely(buf_end - buf >= 16)) {
         __m128i ranges16 = _mm_loadu_si128((const __m128i *)ranges);