Stop building verilator and OTT with gcc-11

Also remove spike build rules as they are no longer needed and spike
doesn't build on the latest gcc

Bypass-Presubmit-Reason: testing manually
Change-Id: Ib270971b39b84d08be9202280728c2521212deeb
diff --git a/platforms/nexus/opentitan_sw.mk b/platforms/nexus/opentitan_sw.mk
index 95e098a..c7da8e8 100644
--- a/platforms/nexus/opentitan_sw.mk
+++ b/platforms/nexus/opentitan_sw.mk
@@ -97,7 +97,6 @@
 opentitan_sw_test: | $(OPENTITAN_BUILD_OUT_DIR) \
                    $(OPENTITAN_BUILD_LOG_DIR)
 	cd $(OPENTITAN_SRC_DIR) && \
-		export CC=gcc-11; export CXX=g++-11; \
 		bazel query "kind(test, //sw/device/...)" | \
 			grep "_unittest" | \
 			xargs bazel test --build_tests_only=false \
diff --git a/platforms/shodan/opentitan_sw.mk b/platforms/shodan/opentitan_sw.mk
index a3a5e8f..6edf08b 100644
--- a/platforms/shodan/opentitan_sw.mk
+++ b/platforms/shodan/opentitan_sw.mk
@@ -77,7 +77,6 @@
 opentitan_sw_test: | $(OPENTITAN_BUILD_OUT_DIR) \
                    $(OPENTITAN_BUILD_LOG_DIR)
 	cd $(OPENTITAN_SRC_DIR) && \
-		export CC=gcc-11; export CXX=g++-11; \
 		bazel query "kind(test, //sw/device/...)" | \
 			grep "_unittest" | \
 			xargs bazel test --build_tests_only=false \
diff --git a/platforms/shodan/sim_tools.mk b/platforms/shodan/sim_tools.mk
index 8bd847e..37bc964 100644
--- a/platforms/shodan/sim_tools.mk
+++ b/platforms/shodan/sim_tools.mk
@@ -12,37 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-SPIKE_SRC_DIR := $(ROOTDIR)/toolchain/spike
-SPIKE_BUILD_DIR := $(OUT)/tmp/spike
-SPIKE_INSTALL_DIR := $(OUT)/host/spike
-
-$(SPIKE_BUILD_DIR):
-	mkdir -p $(SPIKE_BUILD_DIR)
-
-$(SPIKE_INSTALL_DIR):
-	mkdir -p $(SPIKE_INSTALL_DIR)
-
-$(SPIKE_INSTALL_DIR)/bin/spike: $(SPIKE_SRC_DIR) | $(SPIKE_BUILD_DIR) $(SPIKE_INSTALL_DIR)
-	cd $(SPIKE_BUILD_DIR) && \
-	CC=gcc-11 CXX=g++-11 \
-	$(SPIKE_SRC_DIR)/configure --prefix=$(SPIKE_INSTALL_DIR) \
-		--with-isa=rv32imafcv1p0_xspringbok --with-target=riscv32-unknown-elf \
-		--enable-commitlog
-	$(MAKE) -C $(SPIKE_BUILD_DIR) install
-
-## Build spike RISCV ISA simulator
-#
-# Using sources in toolchain/spike, this target builds spike from source and stores
-# its output in out/host/spike.
-#
-# You may want to build with `m -j64 spike` to enable parallel build.
-#
-# To rebuild this target, run `m spike_clean` and re-run.
-spike: $(SPIKE_INSTALL_DIR)/bin/spike
-
-spike_clean:
-	rm -r $(SPIKE_BUILD_DIR) $(SPIKE_INSTALL_DIR)
-
 QEMU_SRC_DIR          := $(ROOTDIR)/toolchain/riscv-qemu
 QEMU_OUT_DIR          := $(OUT)/host/qemu
 QEMU_BINARY           := $(QEMU_OUT_DIR)/riscv32-softmmu/qemu-system-riscv32
@@ -69,5 +38,4 @@
 qemu_clean:
 	rm -rf $(QEMU_OUT_DIR)
 
-.PHONY:: spike spike_clean
 .PHONY:: qemu qemu_clean
diff --git a/platforms/shodan/tbm.mk b/platforms/shodan/tbm.mk
index cf97f05..4593957 100644
--- a/platforms/shodan/tbm.mk
+++ b/platforms/shodan/tbm.mk
@@ -16,7 +16,7 @@
 
 ## Run TBM on the riscv-tests
 # The results are saved in out/tbm/traces/riscv-tests/{benchmarks,isa}/*.tbm_log
-tbm_riscv_tests: tbm spike springbok_riscv_tests
+tbm_riscv_tests: tbm springbok_riscv_tests
 	$(MAKE) -C $(TBM_SRC_DIR) -f riscv_tests.mk riscv_tests
 .PHONY:: tbm_riscv_tests
 
@@ -28,7 +28,7 @@
 
 ## Run TBM on the riscv-tests
 # The results are saved in out/tbm/traces/rvv/*.tbm_log
-tbm_rvv_tests: tbm spike springbok_for_tbm
+tbm_rvv_tests: tbm springbok_for_tbm
 	$(MAKE) -C $(TBM_SRC_DIR) -f rvv_tests.mk rvv_tests
 .PHONY:: tbm_rvv_tests
 
@@ -40,7 +40,7 @@
 
 ## Run TBM on various examples from shodan
 # The results are saved in out/tbm/traces/integration
-tbm_integration_tests: tbm spike iree_no_wmmu springbok
+tbm_integration_tests: tbm iree_no_wmmu springbok
 	$(MAKE) -C $(TBM_SRC_DIR) -f integration-tests.mk integration_tests
 .PHONY:: tbm_integration_tests
 
diff --git a/platforms/sparrow/opentitan_sw.mk b/platforms/sparrow/opentitan_sw.mk
index 95e098a..c7da8e8 100644
--- a/platforms/sparrow/opentitan_sw.mk
+++ b/platforms/sparrow/opentitan_sw.mk
@@ -97,7 +97,6 @@
 opentitan_sw_test: | $(OPENTITAN_BUILD_OUT_DIR) \
                    $(OPENTITAN_BUILD_LOG_DIR)
 	cd $(OPENTITAN_SRC_DIR) && \
-		export CC=gcc-11; export CXX=g++-11; \
 		bazel query "kind(test, //sw/device/...)" | \
 			grep "_unittest" | \
 			xargs bazel test --build_tests_only=false \
diff --git a/verilator.mk b/verilator.mk
index 9560224..6b9e021 100644
--- a/verilator.mk
+++ b/verilator.mk
@@ -29,7 +29,6 @@
 	cd $(VERILATOR_BUILD_DIR) && \
 		autoconf -o $(VERILATOR_BUILD_DIR)/configure $(VERILATOR_SRC_DIR)/configure.ac
 	cd $(VERILATOR_BUILD_DIR) && sh configure \
-		CC=gcc-11 CXX=g++-11 \
 		--srcdir=$(VERILATOR_SRC_DIR) \
 		--prefix=$(VERILATOR_OUT_DIR)
 	$(MAKE) -C $(VERILATOR_BUILD_DIR)