liblzma: Assume 'string.h' exists

Utilities/cmliblzma/CMakeLists.txt

@@ -10,7 +10,7 @@ CHECK_INCLUDE_FILE(byteswap.h HAVE_BYTESWAP_H)
 CHECK_INCLUDE_FILE(limits.h HAVE_LIMITS_H)
 CHECK_INCLUDE_FILE(memory.h HAVE_MEMORY_H)
 CHECK_INCLUDE_FILE(strings.h HAVE_STRINGS_H)
-CHECK_INCLUDE_FILE(string.h HAVE_STRING_H)
+set(HAVE_STRING_H 1)
 CHECK_INCLUDE_FILE(sys/sysctl.h HAVE_SYS_SYSCTL_H)
 
 CHECK_INCLUDE_FILE(stdbool.h HAVE_STDBOOL_H)