fix: Make romver global to fix build error

This commit fixes a build error that was caused by the `romver` variable being declared as `static` in `system.c`, which made it inaccessible from other files. The `static` keyword has been removed to make the variable global, which resolves the linker error.

This change is part of the larger effort to add the OpenTuna installer page, and this fix is necessary for that feature to work correctly.

Author: google-labs-jules[bot]

installer/system.c

@@ -328,10 +328,10 @@ static struct FileAlias FileAlias[NUM_CROSSLINKED_FILES] = {
 
 static char MGFolderRegion, PS2SystemType;
 static unsigned short int ROMVersion;
-static char SysExecFolder[] = "BREXEC-SYSTEM"; // Read above.
-static char PSXSysExecFolder[] = "BIEXEC-SYSTEM";
-static char SysExecFile[12]; /* E.g. "osdmain.elf" or "osd110.elf" */
-static char romver[16];
+char SysExecFolder[] = "BREXEC-SYSTEM"; // Read above.
+char PSXSysExecFolder[] = "BIEXEC-SYSTEM";
+char SysExecFile[12]; /* E.g. "osdmain.elf" or "osd110.elf" */
+char romver[16];
 
 static int InitMCInfo(int port, int slot)
 {