Fix variable initializtion warnings

src/mem/rom.c

@@ -94,7 +94,7 @@ rom_fopen(char *fn, char *mode)
 {
     char temp[1024];
     rom_path_t *rom_path = &rom_paths;
-    FILE *fp;
+    FILE *fp = NULL;
 
     if (strstr(fn, "roms/") == fn) {
         /* Relative path */

src/mem/spd.c

@@ -405,7 +405,7 @@ void
 spd_write_drbs_with_ext(uint8_t *regs, uint8_t reg_min, uint8_t reg_max, uint8_t drb_unit)
 {
     uint8_t row, dimm, drb;
-    uint16_t size, row_val, rows[SPD_MAX_SLOTS];
+    uint16_t size, row_val = 0, rows[SPD_MAX_SLOTS];
     int shift;
 
     /* No SPD: split SIMMs into pairs as if they were "DIMM"s. */

src/qt/qt_deviceconfig.cpp

@@ -117,7 +117,7 @@ void DeviceConfig::ConfigureDevice(const _device_* device, int instance, Setting
             cbox->setObjectName(config->name);
             auto* model = cbox->model();
             int currentIndex = -1;
-            int selected;
+            int selected = 0;
             switch (config->type) {
             case CONFIG_SELECTION:
                 selected = config_get_int(device_context.name, const_cast<char*>(config->name), config->default_int);

src/video/vid_ati_mach64.c

@@ -1283,7 +1283,7 @@ void mach64_blit(uint32_t cpu_dat, int count, mach64_t *mach64)
                 case OP_RECT:
 				while (count)
                 {
-                        uint32_t src_dat, dest_dat;
+                        uint32_t src_dat = 0, dest_dat;
                         uint32_t host_dat = 0;
                         uint32_t old_dest_dat;
                         int mix = 0;