riscv: Clearly separate the build flow for autotools and cmake

Signed-off-by: Cosmin Truta <ctruta@gmail.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index cfc4cc1..9ad991b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -361,6 +361,7 @@
         add_definitions(-DPNG_RISCV_RVV_OPT=2)
       elseif(PNG_RISCV_RVV STREQUAL "check")
         add_definitions(-DPNG_RISCV_RVV_CHECK_SUPPORTED)
+        add_definitions(-DPNG_RISCV_RVV_OPT=1)
       endif()
     else()
       add_definitions(-DPNG_RISCV_RVV_OPT=0)
diff --git a/pngpriv.h b/pngpriv.h
index cb44a6a..e3054b9 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -154,11 +154,7 @@
     * to configure or put -DPNG_RISCV_RVV_OPT=2 in CPPFLAGS.
     */
 
-#  if defined(__riscv) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
-#     define PNG_RISCV_RVV_OPT 1
-#  else
-#     define PNG_RISCV_RVV_OPT 0
-#  endif
+#  define PNG_RISCV_RVV_OPT 0
 #endif
 
 #if PNG_ARM_NEON_OPT > 0