projects/sample: Import adapted form of current LLVM autoconf/Makefile setup so that projects/sample is standalone and not tied to the LLVM build setup.

- This currently just moves over all of the behavior from LLVM. Eventually all of the configure checks that are directly needed by the LLVM build setup should probably go away, and the project should manage their own configuration checks if necessary.

 - This is the 1st half of this work, the actual Makefile.common hasn't moved over yet. I've tried to stage this in such a way that incremental builds will properly reconfigure for most active developers (the Makefiles don't handle reconfiguring in a perfectly reliable way, and I haven't found an easy way to make them do so).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142456 91177308-0d34-0410-b5e6-96231b3b80d8

projects/sample/autoconf/m4/sanity_check.m4

@@ -0,0 +1,31 @@
+dnl Check a program for version sanity. The test runs a program, passes it an
+dnl argument to make it print out some identification string, and filters that 
+dnl output with a regular expression. If the output is non-empty, the program
+dnl passes the sanity check.
+dnl   $1 - Name or full path of the program to run
+dnl   $2 - Argument to pass to print out identification string
+dnl   $3 - grep RE to match identification string
+dnl   $4 - set to 1 to make errors only a warning
+AC_DEFUN([CHECK_PROGRAM_SANITY],
+[
+AC_MSG_CHECKING([sanity for program ]$1)
+sanity="0"
+sanity_path=`which $1 2>/dev/null`
+if test "$?" -eq 0 -a -x "$sanity_path" ; then
+  sanity=`$1 $2 2>&1 | grep "$3"`
+  if test -z "$sanity" ; then
+    AC_MSG_RESULT([no])
+    sanity="0"
+    if test "$4" -eq 1 ; then
+      AC_MSG_WARN([Program ]$1[ failed to pass sanity check.])
+    else
+      AC_MSG_ERROR([Program ]$1[ failed to pass sanity check.])
+    fi
+  else
+    AC_MSG_RESULT([yes])
+    sanity="1"
+  fi
+else
+  AC_MSG_RESULT([not found])
+fi
+])