Fix UBSAN errors in ccache-swig

ccache.c:738:18: runtime error: null pointer passed as argument 1, which is declared to never be null
Fixes stderr redirect in testname CCACHE_CPP2, when the CCACHE_CPP2
environment variable is defined.

mdfour.c:91:20: runtime error: left shift of 139 by 24 places cannot be represented in type 'int'
Looks like this brings some stability to the md4 hash calculation.

Closes swig#2449

Conflicts:
	CHANGES.current

Author: wsfulton

CCache/ccache.c

@@ -735,13 +735,15 @@ static void from_cache(int first)
 	}
 
 	/* send the cpp stderr, if applicable */
-	fd_cpp_stderr = open(cpp_stderr, O_RDONLY | O_BINARY);
-	if (fd_cpp_stderr != -1) {
-		copy_fd(fd_cpp_stderr, 2);
-		close(fd_cpp_stderr);
-		unlink(cpp_stderr);
-		free(cpp_stderr);
-		cpp_stderr = NULL;
+	if (cpp_stderr) {
+		fd_cpp_stderr = open(cpp_stderr, O_RDONLY | O_BINARY);
+		if (fd_cpp_stderr != -1) {
+			copy_fd(fd_cpp_stderr, 2);
+			close(fd_cpp_stderr);
+			unlink(cpp_stderr);
+			free(cpp_stderr);
+			cpp_stderr = NULL;
+		}
 	}
 
 	/* send the stderr */

CCache/mdfour.c

@@ -88,8 +88,8 @@ static void copy64(uint32 *M, const unsigned char *in)
 	int i;
 
 	for (i=0;i<16;i++)
-		M[i] = (in[i*4+3]<<24) | (in[i*4+2]<<16) |
-			(in[i*4+1]<<8) | (in[i*4+0]<<0);
+		M[i] = ((uint32)in[i*4+3]<<24) | ((uint32)in[i*4+2]<<16) |
+			((uint32)in[i*4+1]<<8) | ((uint32)in[i*4+0]<<0);
 }
 
 static void copy4(unsigned char *out,uint32 x)

CHANGES.current

@@ -7,6 +7,10 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.1 (in progress)
 ===========================
 
+2022-11-26: wsfulton
+            #2449 Fix undefined behaviour in ccache-swig calculating md4 hashes and possibly
+            also handling errors when CCACHE_CPP2 is set.
+
 2022-11-25: wsfulton
             #961 Fix syntax error parsing unnamed template parameters with a default value.