patch 8.2.3032: build problems with MSVC, other crypt issues with libsodium

Problem:    Build problems with MSVC, other crypt issues with libsodium.
Solution:   Adjust MSVC makefile. Disable swap file only when 'key' is set.
            Adjust error message used when key is wrong.  Fix Coverity issues.
            (Christian Brabandt, closes #8420, closes #8411)
diff --git a/src/Make_mvc.mak b/src/Make_mvc.mak
index c61bb27..4d6e49b 100644
--- a/src/Make_mvc.mak
+++ b/src/Make_mvc.mak
@@ -42,7 +42,11 @@
 #	Sound support: SOUND=yes (default is yes)
 #
 #	Sodium support: SODIUM=[Path to Sodium directory]
-#	 You need to install the msvc package from https://download.libsodium.org/libsodium/releases/
+#	 Dynamic built with libsodium
+#	 You need to install the msvc package from
+#	 https://download.libsodium.org/libsodium/releases/
+#	 and package the libsodium.dll with Vim
+#
 #
 #	DLL support (EXPERIMENTAL): VIMDLL=yes (default is no)
 #	  Creates vim{32,64}.dll, and stub gvim.exe and vim.exe.
@@ -383,14 +387,14 @@
 ! if "$(CPU)" == "AMD64"
 SOD_LIB		= $(SODIUM)\x64\Release\v140\dynamic
 ! elseif "$(CPU)" == "i386"
-SOD_LIB		= $(SODIUM)\x86\Release\v140\dynamic
+SOD_LIB		= $(SODIUM)\Win32\Release\v140\dynamic
 ! else
 SODIUM = no
 ! endif
 !endif
 
 !if "$(SODIUM)" != "no"
-SOD_INC		= -I $(SODIUM)\include
+SOD_INC		= /I "$(SODIUM)\include"
 SOD_DEFS	= -DFEAT_SODIUM
 SOD_LIB		= $(SOD_LIB)\libsodium.lib
 !endif
@@ -514,7 +518,7 @@
 
 CFLAGS = -c /W3 /GF /nologo $(CVARS) -I. -Iproto -DHAVE_PATHDEF -DWIN32 \
 		$(CSCOPE_DEFS) $(TERM_DEFS) $(SOUND_DEFS) $(NETBEANS_DEFS) $(CHANNEL_DEFS) \
-		$(NBDEBUG_DEFS) $(XPM_DEFS) $(SOD_DEFS) \
+		$(NBDEBUG_DEFS) $(XPM_DEFS) $(SOD_DEFS) $(SOD_INC) \
 		$(DEFINES) -DWINVER=$(WINVER) -D_WIN32_WINNT=$(WINVER)
 
 #>>>>> end of choices
@@ -726,7 +730,7 @@
 
 INCL =	vim.h alloc.h ascii.h ex_cmds.h feature.h errors.h globals.h \
 	keymap.h macros.h option.h os_dos.h os_win32.h proto.h regexp.h \
-	spell.h structs.h term.h beval.h $(NBDEBUG_INCL) $(SOD_INC)
+	spell.h structs.h term.h beval.h $(NBDEBUG_INCL)
 
 OBJ = \
 	$(OUTDIR)\arabic.obj \