Build LLVM with -fno-omit-frame-pointer on Linux

mk/llvm.mk

@@ -9,7 +9,7 @@ ifeq ($(CFG_LLVM_ROOT),)
 
 $$(LLVM_CONFIG_$(1)): $$(LLVM_DEPS_$(1))
 	@$$(call E, make: llvm)
-	$$(Q)$$(MAKE) -C $$(CFG_LLVM_BUILD_DIR_$(1))
+	$$(Q)$$(MAKE) -C $$(CFG_LLVM_BUILD_DIR_$(1)) $$(CFG_LLVM_BUILD_ENV)
 
 endif
 

mk/platform.mk

@@ -64,6 +64,8 @@ ifneq ($(findstring linux,$(CFG_OSTYPE)),)
     endif
   endif
   CFG_INSTALL_NAME =
+  # Linux requires LLVM to be built like this to get backtraces into Rust code
+  CFG_LLVM_BUILD_ENV="CXXFLAGS=-fno-omit-frame-pointer"
 endif
 
 ifneq ($(findstring darwin,$(CFG_OSTYPE)),)