scripts/c: add single-file C port of hbc_mini

hbc_mini.c is a full port of scripts/hbc_mini.py requiring only zlib,
pthreads, and a C11 compiler. Supports Linux, FreeBSD, NetBSD, and
DragonFly BSD with platform-specific plugin backends:

  - cpu_monitor:    /proc/stat (Linux) or kern.cp_time sysctl (BSD)
  - memory_monitor: /proc/meminfo (Linux), vm.stats.vm.* (FreeBSD),
                    struct uvmexp (NetBSD)
  - network_monitor:/proc/net/dev (Linux) or getifaddrs()+if_data (BSD)
  - disk_monitor:   df -P (all platforms)
  - ping_monitor:   ping subprocess (all platforms)
  - nagios_runner:  shell commands with perfdata parsing (all platforms)
  - os_info:        uname() + /etc/os-release (Linux) or kern.osrelease (BSD)

Build: cc -O2 -o hbc_mini hbc_mini.c -lz -lpthread -lm

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/c/Makefile

@@ -0,0 +1,21 @@
+CC      ?= cc
+CFLAGS  = -O2 -Wall -Wextra -std=c11
+LDFLAGS = -lz -lpthread -lm
+TARGET  = hbc_mini
+SRC     = hbc_mini.c
+
+# FreeBSD/NetBSD keep zlib in base; no extra flags needed.
+# On some NetBSD installs pthreads may need -lpthread from pkgsrc.
+
+.PHONY: all clean debug
+
+all: $(TARGET)
+
+$(TARGET): $(SRC)
+	$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)
+
+debug: $(SRC)
+	$(CC) -g -fsanitize=address,undefined -o $(TARGET)_dbg $< $(LDFLAGS)
+
+clean:
+	rm -f $(TARGET) $(TARGET)_dbg