Allow the use of non-Apple compiles

Pre-compiled headers was a performance optimisation available in Apple's
legacy compilers. It was never available in stock GCC and now prevents
nmap from being built with stock GCC since -no-cpp-precomp is not
a recognised option.
Leave the option in should someone wants to try enabling it.

configure

@@ -4550,8 +4550,6 @@ else
 fi
 
 
-needs_cpp_precomp=no
-
 LUA_CFLAGS="-DLUA_USE_POSIX -DLUA_USE_DLOPEN"
 
 
@@ -4890,7 +4888,6 @@ _ACEOF
 fi
 
  LUA_CFLAGS="-DLUA_USE_MACOSX"
- needs_cpp_precomp=yes
  ;;
 esac
 

configure.ac

@@ -106,8 +106,6 @@ fi
 
 AC_PATH_TOOL([STRIP], [strip], [/bin/true])
 
-needs_cpp_precomp=no
-
 LUA_CFLAGS="-DLUA_USE_POSIX -DLUA_USE_DLOPEN"
 
 AH_TEMPLATE(SOLARIS, [Sun/Oracle Solaris])
@@ -196,7 +194,6 @@ case "$host" in
  dnl on Mac OSX the math library seems to contain unwanted getopt cruft
  AC_CHECK_LIB(m, main)
  LUA_CFLAGS="-DLUA_USE_MACOSX"
- needs_cpp_precomp=yes
  ;;
 esac
 

nping/configure

@@ -4292,8 +4292,6 @@ else
 fi
 
 
-needs_cpp_precomp=no
-
 ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'
 ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -6258,7 +6256,6 @@ _ACEOF
 
 fi
 
- needs_cpp_precomp=yes
  ;;
 esac
 

nping/configure.ac

@@ -103,8 +103,6 @@ fi
 
 AC_PATH_TOOL([STRIP], [strip], [/bin/true])
 
-needs_cpp_precomp=no
-
 dnl Checks for header files.
 AC_CHECK_HEADERS(pwd.h termios.h sys/sockio.h)
 
@@ -540,7 +538,6 @@ case "$host" in
  AC_DEFINE(MACOSX, 1, [Apple OS X])
  dnl on Mac OSX the math library seems to contain unwanted getopt cruft
  AC_CHECK_LIB(m, main)
- needs_cpp_precomp=yes
  ;;
 esac