Check whether cargo exists and disable the blazesym feature. (iovisor…

…#4227)

refs:
  iovisor#4223
  https://github.com/libbpf/libbpf-bootstrap/blob/938651fcef787f3885b7c32792851f8423bf8421/examples/c/Makefile#L24-L32

libbpf-tools/Makefile

@@ -18,8 +18,13 @@ ARCH := $(shell uname -m | sed 's/x86_64/x86/' | sed 's/aarch64/arm64/' \
  | sed 's/riscv64/riscv/' | sed 's/loongarch.*/loongarch/')
 BTFHUB_ARCHIVE ?= $(abspath btfhub-archive)
 ifeq ($(ARCH),x86)
+CARGO ?= $(shell which cargo)
+ifeq ($(strip $(CARGO)),)
+USE_BLAZESYM ?= 0
+else
 USE_BLAZESYM ?= 1
 endif
+endif
 
 ifeq ($(wildcard $(ARCH)/),)
 $(error Architecture $(ARCH) is not supported yet. Please open an issue)