windows: correct CertOpenStore to expect a 0 return value on failure

According to [1], this function returns NULL when it errors, rather than
INVALID_HANDLE_VALUE, which other Win32 functions return. Quick reversing
indicates that [1] is correct, as there's a `xor eax, eax` in the error
paths of the function just before jumping to the epilogue.

[1] https://docs.microsoft.com/en-us/windows/win32/api/wincrypt/nf-wincrypt-certopenstore#return-value

Change-Id: Iafe3b9c78e92c9c5adb8d14a434e11b58f59f19b
GitHub-Last-Rev: 5fcd21d88936322645b1ab296309644b85869b87
GitHub-Pull-Request: golang/sys#92
Reviewed-on: https://go-review.googlesource.com/c/sys/+/273446
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Trust: Alex Brainman <alex.brainman@gmail.com>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
diff --git a/windows/syscall_windows.go b/windows/syscall_windows.go
index 6c2ff27..c71bad1 100644
--- a/windows/syscall_windows.go
+++ b/windows/syscall_windows.go
@@ -260,7 +260,7 @@
 //sys	TransmitFile(s Handle, handle Handle, bytesToWrite uint32, bytsPerSend uint32, overlapped *Overlapped, transmitFileBuf *TransmitFileBuffers, flags uint32) (err error) = mswsock.TransmitFile
 //sys	ReadDirectoryChanges(handle Handle, buf *byte, buflen uint32, watchSubTree bool, mask uint32, retlen *uint32, overlapped *Overlapped, completionRoutine uintptr) (err error) = kernel32.ReadDirectoryChangesW
 //sys	CertOpenSystemStore(hprov Handle, name *uint16) (store Handle, err error) = crypt32.CertOpenSystemStoreW
-//sys   CertOpenStore(storeProvider uintptr, msgAndCertEncodingType uint32, cryptProv uintptr, flags uint32, para uintptr) (handle Handle, err error) [failretval==InvalidHandle] = crypt32.CertOpenStore
+//sys   CertOpenStore(storeProvider uintptr, msgAndCertEncodingType uint32, cryptProv uintptr, flags uint32, para uintptr) (handle Handle, err error) = crypt32.CertOpenStore
 //sys	CertEnumCertificatesInStore(store Handle, prevContext *CertContext) (context *CertContext, err error) [failretval==nil] = crypt32.CertEnumCertificatesInStore
 //sys   CertAddCertificateContextToStore(store Handle, certContext *CertContext, addDisposition uint32, storeContext **CertContext) (err error) = crypt32.CertAddCertificateContextToStore
 //sys	CertCloseStore(store Handle, flags uint32) (err error) = crypt32.CertCloseStore
diff --git a/windows/zsyscall_windows.go b/windows/zsyscall_windows.go
index 204b1db..03e9f18 100644
--- a/windows/zsyscall_windows.go
+++ b/windows/zsyscall_windows.go
@@ -1193,7 +1193,7 @@
 func CertOpenStore(storeProvider uintptr, msgAndCertEncodingType uint32, cryptProv uintptr, flags uint32, para uintptr) (handle Handle, err error) {
 	r0, _, e1 := syscall.Syscall6(procCertOpenStore.Addr(), 5, uintptr(storeProvider), uintptr(msgAndCertEncodingType), uintptr(cryptProv), uintptr(flags), uintptr(para), 0)
 	handle = Handle(r0)
-	if handle == InvalidHandle {
+	if handle == 0 {
 		err = errnoErr(e1)
 	}
 	return