Test interopWithC.chpl in --library mode by adding interopWithChpl.test.c (chapel-lang#26762)

[reviewed by @lydia-duncan and @ShreyasKhandekar ]

Our test system wasn't testing a compilation that our Makefile did,
which led to Cray/chapel-private#7145 creeping
into the code base, later fixed by
chapel-lang#26741. Here, I'm adding a C
test that compiles interopWithC.chpl as a library to lock that in and
reduce the chances of such a divergence happening again.

I did not do more than verify that the test output was what I'd expect
given the interopWithC.good file and the calls that the new test adds.
Maybe more importantly, I didn't do anything to review the primer from a
readability/comprehensibility standpoint since I wasn't really changing
its contents, just adding a C file to exercise them more.

Resolves chapel-lang#26751.

Author: bradcray

test/release/examples/primers/interopWithChpl.cleanfiles

@@ -0,0 +1,2 @@
+lib/interopWithC.h
+lib/libinteropWithC.a

test/release/examples/primers/interopWithChpl.good

@@ -0,0 +1,10 @@
+Sum of Array: 55
+20
+11
+(x = 5)
+(x = 120)
+9.0
+Called foo()
+14
+14
+17

test/release/examples/primers/interopWithChpl.lastcompopts

@@ -0,0 +1 @@
+-Llib/ -linteropWithC `$CHPL_HOME/util/config/compileline --libraries`

test/release/examples/primers/interopWithChpl.precomp

@@ -0,0 +1,3 @@
+#!/bin/bash
+echo Compiling interopWithC.chpl
+$3 --library --static interopWithC.chpl

test/release/examples/primers/interopWithChpl.test.c

@@ -0,0 +1,17 @@
+#include "lib/interopWithC.h"
+
+int main(int argc, char* argv[]) {
+  // initialize the library's copy of the Chapel runtime
+  chpl_library_init(argc, argv);
+
+  // execute the module initialization (module-level code) for
+  // 'interopWithC', including that of any modules it uses or imports
+  chpl__init_interopWithC(1, 2);
+
+  // call its exported routines
+  foo();
+  alsoCallsBaz();
+  callUseMyType();
+
+  chpl_library_finalize();
+}