How to fix valgrind ignoring sigreturn errors on mac os x high sierra.

readme.txt

git clone https://sourceware.org/git/valgrind.git;
cd valgrind/

# time to edit some files (see below)
./autogen.sh
./configure --disable-dependency-tracking --enable-only64bit --build=amd64-darwin
./make
./make install
# done.

syswrap-darwin.c(lines 9050 through 9070)

if (ARG2 == VKI_UC_SET_ALT_STACK) {
      /* This is confusing .. the darwin kernel sources imply there is
         a per-thread on-altstack/not-on-altstack flag, which is set
         by this flag.  Just ignore it and claim success for the time
         being. */
      // VG_(debugLog)(0, "syswrap-darwin",                              // how about we don't print out anything here? - sep 20, 2018 by skunkworker
      //                  "WARNING: Ignoring sigreturn( ..., "
      //                  "UC_SET_ALT_STACK );\n");
     
      SET_STATUS_Success(0);
      return;
   }
   if (ARG2 == VKI_UC_RESET_ALT_STACK) {
      /* Ditto */
      // VG_(debugLog)(0, "syswrap-darwin",                              // or here
      //                  "WARNING: Ignoring sigreturn( ..., "
      //                  "UC_RESET_ALT_STACK );\n");
      SET_STATUS_Success(0);
      return;
   }