Add `dynlib.initialize_symbols` (#3071)

```
package example

import "core:dynlib"
import "core:fmt"

Symbols :: struct {
	// `foo_` is prefixed, so we look for the symbol `foo_add`.
	add: proc "c" (int, int) -> int,
	// We use the tag here to override the symbol to look for, namely `bar_sub`.
	sub: proc "c" (int, int) -> int `dynlib:"bar_sub"`,

	// Exported global (if exporting an i32, the type must be ^i32 because the symbol is a pointer to the export.)
	// If it's not a pointer or procedure type, we'll skip the struct field.
	hellope: ^i32,

	// Handle to free library.
	// We can have more than one of these so we can match symbols for more than one DLL with one struct.
	_my_lib_handle: dynlib.Library,
}

main :: proc() {
	sym: Symbols

	// Load symbols from `lib.dll` into Symbols struct.
	// Each struct field is prefixed with `foo_` before lookup in the DLL's symbol table.
	// The library's Handle (to unload) will be stored in `sym._my_lib_handle`. This way you can load multiple DLLs in one struct.
	count := dynlib.initialize_symbols(&sym, "lib.dll", "foo_", "_my_lib_handle")
	defer dynlib.unload_library(sym._my_lib_handle)
	fmt.printf("%v symbols loaded from lib.dll (%p).\n", count, sym._my_lib_handle)

	if count > 0 {
		fmt.println("42 + 42 =", sym.add(42, 42))
		fmt.println("84 - 13 =", sym.sub(84, 13))
		fmt.println("hellope =", sym.hellope^)
	}
}
```

1 files changed, 36 insertions, 0 deletions

diff --git a/core/dynlib/example/example.odin b/core/dynlib/example/example.odin
new file mode 100644
index 000000000..7a6368d59
--- /dev/null
+++ b/core/dynlib/example/example.odin
@@ -0,0 +1,36 @@
+package example
+
+import "core:dynlib"
+import "core:fmt"
+
+Symbols :: struct {
+	// `foo_` is prefixed, so we look for the symbol `foo_add`.
+	add: proc "c" (int, int) -> int,
+	// We use the tag here to override the symbol to look for, namely `bar_sub`.
+	sub: proc "c" (int, int) -> int `dynlib:"bar_sub"`,
+
+	// Exported global (if exporting an i32, the type must be ^i32 because the symbol is a pointer to the export.)
+	// If it's not a pointer or procedure type, we'll skip the struct field.
+	hellope: ^i32,
+
+	// Handle to free library.
+	// We can have more than one of these so we can match symbols for more than one DLL with one struct.
+	_my_lib_handle: dynlib.Library,
+}
+
+main :: proc() {
+	sym: Symbols
+
+	// Load symbols from `lib.dll` into Symbols struct.
+	// Each struct field is prefixed with `foo_` before lookup in the DLL's symbol table.
+	// The library's Handle (to unload) will be stored in `sym._my_lib_handle`. This way you can load multiple DLLs in one struct.
+	count := dynlib.initialize_symbols(&sym, "lib.dll", "foo_", "_my_lib_handle")
+	defer dynlib.unload_library(sym._my_lib_handle)
+	fmt.printf("%v symbols loaded from lib.dll (%p).\n", count, sym._my_lib_handle)
+
+	if count > 0 {
+		fmt.println("42 + 42 =", sym.add(42, 42))
+		fmt.println("84 - 13 =", sym.sub(84, 13))
+		fmt.println("hellope =", sym.hellope^)
+	}
+}
\ No newline at end of file