Activate Stack Cookies on GCC5 Builds

Description

Now that a cross-compiler implementation of stack cookies is available,
stack cookies can be enabled for GCC5 builds.

- [x] Impacts functionality?
  - **Functionality** - Does the change ultimately impact how firmware functions?
  - Examples: Add a new library, publish a new PPI, update an algorithm, ...
- [x] Impacts security?
  - **Security** - Does the change have a direct security impact on an application,
    flow, or firmware?
  - Examples: Crypto algorithm change, buffer overflow fix, parameter
    validation improvement, ...
- [x] Breaking change?
  - **Breaking change** - Will anyone consuming this change experience a break
    in build or boot behavior?
  - Examples: Add a new library class, move a module to a different repo, call
    a function in a new library class in a pre-existing module, ...
- [ ] Includes tests?
  - **Tests** - Does the change include any explicit test code?
  - Examples: Unit tests, integration tests, robot tests, ...
- [ ] Includes documentation?
  - **Documentation** - Does the change contain explicit documentation additions
    outside direct code modifications (and comments)?
  - Examples: Update readme file, add feature readme file, link to documentation
    on an a separate Web page, ...

How This Was Tested

Tested on GCC and VS builds of Q35

Integration Instructions

Platforms building with GCC5 and utilize the MdeModulePkg
tools_def.template will need to include a StackCheckLib instance
in their build.

```
[LibraryClasses.X64]
  NULL|MdePkg/Library/StackCheckLib/StackCheckLib.inf
  StackCheckFailureLib|MdePkg/Library/StackCheckFailureLibNull/StackCheckFailureLibNull.inf
```

BaseTools/Conf/tools_def.template

@@ -944,7 +944,7 @@ DEFINE GCC_DEPS_FLAGS              = -MMD -MF $@.deps
 DEFINE GCC48_ALL_CC_FLAGS            = DEF(GCC_ALL_CC_FLAGS) -ffunction-sections -fdata-sections -DSTRING_ARRAY_NAME=$(BASE_NAME)Strings
 DEFINE GCC48_IA32_X64_DLINK_COMMON   = -nostdlib -Wl,-n,-q,--gc-sections -z common-page-size=0x20
 DEFINE GCC48_IA32_CC_FLAGS           = DEF(GCC48_ALL_CC_FLAGS) -m32 -march=i586 -malign-double -fno-stack-protector -D EFI32 -fno-asynchronous-unwind-tables -Wno-address -fno-omit-frame-pointer
-DEFINE GCC48_X64_CC_FLAGS            = DEF(GCC48_ALL_CC_FLAGS) -m64 -fno-stack-protector "-DEFIAPI=__attribute__((ms_abi))" -maccumulate-outgoing-args -mno-red-zone -Wno-address -mcmodel=small -fpie -fno-asynchronous-unwind-tables -Wno-address  -fno-omit-frame-pointer
+DEFINE GCC48_X64_CC_FLAGS            = DEF(GCC48_ALL_CC_FLAGS) -m64 -fstack-protector-strong -mstack-protector-guard=global "-DEFIAPI=__attribute__((ms_abi))" -maccumulate-outgoing-args -mno-red-zone -Wno-address -mcmodel=small -fpie -fno-asynchronous-unwind-tables -Wno-address  -fno-omit-frame-pointer
 DEFINE GCC48_IA32_X64_ASLDLINK_FLAGS = DEF(GCC48_IA32_X64_DLINK_COMMON) -Wl,--entry,ReferenceAcpiTable -u ReferenceAcpiTable
 DEFINE GCC48_IA32_X64_DLINK_FLAGS    = DEF(GCC48_IA32_X64_DLINK_COMMON) -Wl,--entry,$(IMAGE_ENTRY_POINT) -u $(IMAGE_ENTRY_POINT) -Wl,-Map,$(DEST_DIR_DEBUG)/$(BASE_NAME).map,--whole-archive
 DEFINE GCC48_IA32_DLINK2_FLAGS       = -Wl,--defsym=PECOFF_HEADER_SIZE=0x220 DEF(GCC_DLINK2_FLAGS_COMMON)