Revert "also use DESTDIR in makefile.m{ingw,svc}"

This reverts commit 1655e63c49d023bb130741c00fb21694164b7980.

As of @karel-m [1]

"I am not sure whether DESTDIR concept make sense for MS Windows
paths. For example: `make -f makefile.mingw DESTDIR=c:\builddir\
PREFIX=c:\installdir` means that `"$(DESTDIR)$(PREFIX)\bin"` will
expand to `"c:\builddir\c:\installdir\bin"` which is obviously
invalid.
I propose reverting `also use DESTDIR in makefile.m{ingw,svc}`."

[1] https://github.com/libtom/libtomcrypt/pull/234#issuecomment-310366602

makefile.mingw

@@ -15,7 +15,6 @@
 #
 
 #The following can be overridden from command line e.g. make -f makefile.mingw CC=gcc ARFLAGS=rcs
-DESTDIR   =
 PREFIX    = c:\mingw
 CC        = gcc
 AR        = ar
@@ -264,20 +263,20 @@ clean:
 
 #Install the library + headers
 install: $(LIBMAIN_S) $(LIBMAIN_I) $(LIBMAIN_D)
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\bin" mkdir "$(DESTDIR)$(PREFIX)\bin"
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\lib" mkdir "$(DESTDIR)$(PREFIX)\lib"
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\include" mkdir "$(DESTDIR)$(PREFIX)\include"
-	copy /Y $(LIBMAIN_S) "$(DESTDIR)$(PREFIX)\lib"
-	copy /Y $(LIBMAIN_I) "$(DESTDIR)$(PREFIX)\lib"
-	copy /Y $(LIBMAIN_D) "$(DESTDIR)$(PREFIX)\bin"
-	copy /Y src\headers\tomcrypt*.h "$(DESTDIR)$(PREFIX)\include"
+	cmd /c if not exist "$(PREFIX)\bin" mkdir "$(PREFIX)\bin"
+	cmd /c if not exist "$(PREFIX)\lib" mkdir "$(PREFIX)\lib"
+	cmd /c if not exist "$(PREFIX)\include" mkdir "$(PREFIX)\include"
+	copy /Y $(LIBMAIN_S) "$(PREFIX)\lib"
+	copy /Y $(LIBMAIN_I) "$(PREFIX)\lib"
+	copy /Y $(LIBMAIN_D) "$(PREFIX)\bin"
+	copy /Y src\headers\tomcrypt*.h "$(PREFIX)\include"
 
 #Install useful tools
 install_bins: hashsum
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\bin" mkdir "$(DESTDIR)$(PREFIX)\bin"
-	copy /Y hashsum.exe "$(DESTDIR)$(PREFIX)\bin"
+	cmd /c if not exist "$(PREFIX)\bin" mkdir "$(PREFIX)\bin"
+	copy /Y hashsum.exe "$(PREFIX)\bin"
 
 #Install documentation
 install_docs: doc/crypt.pdf
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\doc" mkdir "$(DESTDIR)$(PREFIX)\doc"
-	copy /Y doc\crypt.pdf "$(DESTDIR)$(PREFIX)\doc"
+	cmd /c if not exist "$(PREFIX)\doc" mkdir "$(PREFIX)\doc"
+	copy /Y doc\crypt.pdf "$(PREFIX)\doc"

makefile.msvc

@@ -15,7 +15,6 @@
 #
 
 #The following can be overridden from command line e.g. make -f makefile.msvc CC=gcc ARFLAGS=rcs
-DESTDIR   =
 PREFIX    = c:\devel
 CFLAGS    = /Ox /DUSE_LTM /DLTM_DESC /I../libtommath
 EXTRALIBS = ../libtommath/tommath.lib
@@ -251,18 +250,18 @@ clean:
 
 #Install the library + headers
 install: $(LIBMAIN_S)
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\bin" mkdir "$(DESTDIR)$(PREFIX)\bin"
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\lib" mkdir "$(DESTDIR)$(PREFIX)\lib"
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\include" mkdir "$(DESTDIR)$(PREFIX)\include"
-	copy /Y $(LIBMAIN_S) "$(DESTDIR)$(PREFIX)\lib"
-	copy /Y src\headers\tomcrypt*.h "$(DESTDIR)$(PREFIX)\include"
+	cmd /c if not exist "$(PREFIX)\bin" mkdir "$(PREFIX)\bin"
+	cmd /c if not exist "$(PREFIX)\lib" mkdir "$(PREFIX)\lib"
+	cmd /c if not exist "$(PREFIX)\include" mkdir "$(PREFIX)\include"
+	copy /Y $(LIBMAIN_S) "$(PREFIX)\lib"
+	copy /Y src\headers\tomcrypt*.h "$(PREFIX)\include"
 
 #Install useful tools
 install_bins: hashsum
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\bin" mkdir "$(DESTDIR)$(PREFIX)\bin"
-	copy /Y hashsum.exe "$(DESTDIR)$(PREFIX)\bin"
+	cmd /c if not exist "$(PREFIX)\bin" mkdir "$(PREFIX)\bin"
+	copy /Y hashsum.exe "$(PREFIX)\bin"
 
 #Install documentation
 install_docs: doc/crypt.pdf
-	cmd /c if not exist "$(DESTDIR)$(PREFIX)\doc" mkdir "$(DESTDIR)$(PREFIX)\doc"
-	copy /Y doc\crypt.pdf "$(DESTDIR)$(PREFIX)\doc"
+	cmd /c if not exist "$(PREFIX)\doc" mkdir "$(PREFIX)\doc"
+	copy /Y doc\crypt.pdf "$(PREFIX)\doc"