Add test program testapi_modern.c (#7760)

* Add test program testapi_modern.c

This makes sure the issue #4518 is preserved.  The test fails for now (well we need to add an actual testing of the output) but this lets us play in the debugger.

* Add test and PS file in DVC

The C code will make a plot to be compared with the CLI expected plot.

src/testapi_modern.c

@@ -0,0 +1,23 @@
+/* Issue from GitHub: https://github.com/GenericMappingTools/gmt/issues/4518
+ * Problem seems to be that gmt begin comes after GMT_Create_Session in the
+ * code so there are orientation and page size issues. In gmt end, the
+ * psconvert call is missing the -A.
+ *
+ * See test script api/apimodern.sh
+ */
+
+#include "gmt.h"
+
+int main () {
+	void *API = NULL;
+
+	/* Initialize the GMT session */
+	if ((API = GMT_Create_Session ("testapi_modern", 2, GMT_SESSION_RUNMODE, NULL)) == NULL)
+		 return EXIT_FAILURE;
+	GMT_Call_Module(API, "begin", GMT_MODULE_CMD, "apimodern ps");
+	GMT_Call_Module(API, "basemap", GMT_MODULE_CMD, "-BWESN -Bafg -JM7.27/42.27/16.25c -R5.5/41.425/9.0/43.1+r");
+	GMT_Call_Module(API, "end", GMT_MODULE_CMD, "show");
+	/* Destroy session */
+	if (GMT_Destroy_Session (API))
+		return EXIT_FAILURE;
+}

test/api/apimodern.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+# 
+# Purpose: This is a CLI version of what testapi_modern.c should produce
+# Fails until we fix the page size and orientation from the C program.
+
+# This is the fixed baseline DVC plot we will compare with
+#gmt begin apimodern ps
+#	gmt set PS_MEDIA letter
+#	gmt basemap -BWESN -Bafg -JM7.27/42.27/16.25c -R5.5/41.425/9.0/43.1+r
+#gmt end show
+
+# Run the C code to produce apimodern.ps
+testapi_modern
+ps=apimodern.ps

test/baseline/api.dvc

@@ -1,5 +1,5 @@
 outs:
-- md5: b985dda50abc7f6dcceb4a8848e0a83a.dir
-  size: 3041741
-  nfiles: 16
+- md5: b02bb074d97d27aaec4f9d515ebfdc00.dir
+  size: 3066737
+  nfiles: 17
   path: api