Merge branch with several fixes for Coverity 8.5 warnings

See https://github.com/wxWidgets/wxWidgets/pull/505

src/common/quantize.cpp

@@ -1428,6 +1428,7 @@ void wxQuantize::DoQuantize(unsigned w, unsigned h, unsigned char **in_rows, uns
     j_decompress dec;
     my_cquantize_ptr cquantize;
 
+    dec.colormap = NULL;
     dec.output_width = w;
     dec.desired_number_of_colors = desiredNoColours;
     prepare_range_limit_table(&dec);

src/common/wxcrt.cpp

@@ -685,7 +685,8 @@ int wxVsnprintf(wchar_t *str, size_t size, const wxString& format, va_list argpt
 
     // VsnprintfTestCase reveals that glibc's implementation of vswprintf
     // doesn't nul terminate on truncation.
-    str[size - 1] = 0;
+    if ( size )
+        str[size - 1] = 0;
 
     return rv;
 }

src/generic/timectrlg.cpp

@@ -446,6 +446,7 @@ private:
 
             case Field_Max:
                 wxFAIL_MSG( "Invalid field" );
+                return;
         }
 
         UpdateText();
@@ -531,6 +532,7 @@ private:
             case Field_AMPM:
             case Field_Max:
                 wxFAIL_MSG( "Invalid field" );
+                return;
         }
 
         if ( moveToNextField && m_currentField < Field_Sec )

src/unix/dialup.cpp

@@ -559,6 +559,7 @@ wxDialUpManagerImpl::NetConnection wxDialUpManagerImpl::CheckConnect()
    serv_addr.sin_family = hp->h_addrtype;
    memcpy(&serv_addr.sin_addr,hp->h_addr, hp->h_length);
    serv_addr.sin_port = htons(m_BeaconPort);
+   memset(&serv_addr.sin_zero, 0, sizeof(serv_addr.sin_zero));
 
    int sockfd;
    if( ( sockfd = socket(hp->h_addrtype, SOCK_STREAM, 0)) < 0)

src/unix/utilsunx.cpp

@@ -1209,7 +1209,12 @@ wxMemorySize wxGetFreeMemory()
                     {
                         unsigned long cached;
                         if ( sscanf(buf, "Cached: %lu", &cached) == 1 )
-                            memFree += cached;
+                        {
+                            if ( cached > ULONG_MAX-memFree )
+                                memFree = ULONG_MAX;
+                            else
+                                memFree += cached;
+                        }
                     }
 
                     // values here are always expressed in kB and we want bytes