BaseTools/build_rule.template: Set additional Rust module linker flags (

microsoft#1098)

## Description

This change sets the ImageBase in the PE header for Rust modules to `0`
so they do not have a preferred base. This is similar to the EFI images
produced by the edk2 build system. The subsystem type is also set to
`efi_boot_service_driver` instead of the default target specification
value of `EFI_APPLICATION`. Details for changing the subsystem type are
here:

https://doc.rust-lang.org/nightly/rustc/platform-support/unknown-uefi.html#requirements

Ideally, these values would be set as individual
`target.<triple>.rustflags` in `.cargo/config.toml`. However, we
override the `/MAP` argument using `-C linker-args` in `build_rule.txt`
to the build output directory. This must be set dynamically since the
output directory and module name are based on per module values.

Since the cargo configuration file does not support reading environment
variables and setting an environment there in a `[env]` section would be
too late to impact the commands that run in `build_rules.txt` (cargo is
called from cargo make based on those rules), this is the simplest
approach to retain the map file path in addition to the new changes.

In the future, this may be moved to a common target specification so the
values are available without these changes.

- [ ] Impacts functionality?
- [ ] Impacts security?
- [x] Breaking change?
- [ ] Includes tests?
- [ ] Includes documentation?

## How This Was Tested

- Checked `ImageBase` and `Subsystem` of EFI images in output directory
  to confirm expected values.

## Integration Instructions

This change is marked as breaking in case flows were dependent on the
previous behavior. Otherwise, no changes are nedeed.

Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>

BaseTools/Conf/build_rule.template

@@ -276,7 +276,7 @@
         $(OUTPUT_DIR)(+)$(MODULE_NAME)rust.lib
 
     <Command>
-        $(CARGO) make $(CARGOMAKE_FLAGS) -e FEATURES=$(CARGO_FEATURES) -e RUSTFLAGS="-C link-arg=/MAP:$(DEBUG_DIR)(+)$(MODULE_NAME).map $(RUST_FLAGS)" build $(MODULE_NAME)
+        $(CARGO) make $(CARGOMAKE_FLAGS) -e FEATURES=$(CARGO_FEATURES) -e RUSTFLAGS="-C link-arg=/MAP:$(DEBUG_DIR)(+)$(MODULE_NAME).map -C link-arg=/base:0x0 -C link-arg=/subsystem:efi_boot_service_driver $(RUST_FLAGS)" build $(MODULE_NAME)
         $(CP) $(DEBUG_DIR)(+)$(TARGET_TRIPLE)(+)$(RUST_TARGET)(+)*.a $(DEBUG_DIR)(+)$(MODULE_NAME)rust.lib
         $(CP) $(DEBUG_DIR)(+)$(TARGET_TRIPLE)(+)$(RUST_TARGET)(+)*.a $(OUTPUT_DIR)(+)$(MODULE_NAME)rust.lib
 
@@ -288,7 +288,7 @@
         $(OUTPUT_DIR)(+)$(MODULE_NAME).efi
 
     <Command>
-        $(CARGO) make $(CARGOMAKE_FLAGS) -e FEATURES=$(CARGO_FEATURES) -e RUSTFLAGS="-C link-arg=/MAP:$(DEBUG_DIR)(+)$(MODULE_NAME).map $(RUST_FLAGS)" build $(MODULE_NAME)
+        $(CARGO) make $(CARGOMAKE_FLAGS) -e FEATURES=$(CARGO_FEATURES) -e RUSTFLAGS="-C link-arg=/MAP:$(DEBUG_DIR)(+)$(MODULE_NAME).map -C link-arg=/base:0x0 -C link-arg=/subsystem:efi_boot_service_driver $(RUST_FLAGS)" build $(MODULE_NAME)
         "$(GENFW)" -e $(MODULE_TYPE) -o $(DEBUG_DIR)(+)$(MODULE_NAME).efi $(DEBUG_DIR)(+)$(TARGET_TRIPLE)(+)$(RUST_TARGET)(+)$(MODULE_NAME).efi $(GENFW_FLAGS)
         $(CP) $(DEBUG_DIR)(+)$(MODULE_NAME).map  $(OUTPUT_DIR)(+)$(MODULE_NAME).map
         $(CP) $(DEBUG_DIR)(+)$(MODULE_NAME).efi $(OUTPUT_DIR)(+)$(MODULE_NAME).efi