Fix infinite loops on archs where char is unsigned by default (arm* and powerpc),
because EOF cannot be reached with an unsigned char there.

Index: src/serialize.c
--- src/serialize.c.orig
+++ src/serialize.c
@@ -41,7 +41,7 @@ int storeLocalmotion(FILE* f, const LocalMotion* lm){
 /// restore local motion from file
 LocalMotion restoreLocalmotion(FILE* f){
   LocalMotion lm;
-  char c;
+  int c;
   if(fscanf(f,"(LM %i %i %i %i %i %lf %lf", &lm.v.x,&lm.v.y,&lm.f.x,&lm.f.y,&lm.f.size,
             &lm.contrast, &lm.match) != 7) {
     vs_log_error(modname, "Cannot parse localmotion!\n");
@@ -71,7 +71,7 @@ int vsStoreLocalmotions(FILE* f, const LocalMotions* l
 LocalMotions vsRestoreLocalmotions(FILE* f){
   LocalMotions lms;
   int i;
-  char c;
+  int c;
   int len;
   vs_vector_init(&lms,0);
   if(fscanf(f,"List %i [", &len) != 1) {
@@ -128,7 +128,7 @@ int vsReadFileVersion(FILE* f){
 }
 
 int vsReadFromFile(FILE* f, LocalMotions* lms){
-  char c = fgetc(f);
+  int c = fgetc(f);
   if(c=='F') {
     int num;
     if(fscanf(f,"rame %i (", &num)!=1) {