c-tooling: handle first time orca install

The first time a user installs orca.exe and then runs orca update, the
current_version file doesn't exist yet, so this commit handles that case
by just installing the latest version without attempting to update cli
tool, and writing that version to the current_version file.

src/tool/update.c

@@ -100,31 +100,36 @@ int update(int argc, char** argv)
 	//-----------------------------------------------------------------------------
 	// update cli tool executable
 	//-----------------------------------------------------------------------------
-	{
-		oc_str8 current_version_path = oc_path_append(&arena, orca_dir, OC_STR8("current_version"));
-		oc_file file = oc_file_open(current_version_path, OC_FILE_ACCESS_READ, OC_FILE_OPEN_NONE);
-		if(oc_file_is_nil(file))
-		{
-			fprintf(stderr, "error: failed to identify current Orca version\n");
-			return 1;
-		}
-		oc_str8 current_version = {0};
-		current_version.len = oc_file_size(file);
-		current_version.ptr = oc_arena_push(&arena, current_version.len + 1);
-		oc_file_read(file, current_version.len, current_version.ptr);
-		if(oc_file_last_error(file) != OC_IO_OK)
-		{
-			fprintf(stderr, "error: failed to identify current Orca version\n");
-			return 1;
-		}
-		oc_file_close(file);
+    oc_str8 current_version_path = oc_path_append(&arena, orca_dir, OC_STR8("current_version"));
+    if(oc_sys_exists(current_version_path))
+    {
+        oc_file file = oc_file_open(current_version_path, OC_FILE_ACCESS_READ, OC_FILE_OPEN_NONE);
+        if(oc_file_is_nil(file))
+        {
+            fprintf(stderr, "error: failed to identify current Orca version\n");
+            return 1;
+        }
+        oc_str8 current_version = {0};
+        current_version.len = oc_file_size(file);
+        current_version.ptr = oc_arena_push(&arena, current_version.len + 1);
+        oc_file_read(file, current_version.len, current_version.ptr);
+        if(oc_file_last_error(file) != OC_IO_OK)
+        {
+            fprintf(stderr, "error: failed to identify current Orca version\n");
+            return 1;
+        }
+        oc_file_close(file);
 
-		current_version = oc_str8_trim_space(current_version);
-		if(oc_str8_cmp(current_version, version) != 0)
-		{
-			return replace_yourself_and_update(curl, repo_url_base, orca_dir, current_version, version);
-		}
-	}
+        current_version = oc_str8_trim_space(current_version);
+        if(oc_str8_cmp(current_version, version) != 0)
+        {
+            return replace_yourself_and_update(curl, repo_url_base, orca_dir, current_version, version);
+        }
+    }
+    // NOTE(shaw): if current_version file doesn't exist, then we assume that
+    // the user has just installed the cli tool for the first time, so proceed
+    // with downloading the latest version and writing that version to the
+    // current_version file
 
 	//-----------------------------------------------------------------------------
 	// download and extract latest version