Fix failing tests for zlib-ng

Fedora, at the very least, now packages zlib-ng as zlib. This means the
version reported for the dependency is now X.Y.Z.zlib-ng by pkgconfig
whereas the test expected X.Y.Z. Make the version check work for both
regular zlib and zlib-ng.

test cases/linuxlike/1 pkg-config/prog-checkver.c

@@ -1,11 +1,38 @@
 #include <zlib.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 
+static bool check_version(const char *zlib_ver, const char *found_zlib) {
+#ifdef ZLIBNG_VERSION
+    const char *ptr = strstr(zlib_ver, found_zlib);
+
+    // If the needle isn't found or the needle isn't at the start, fail.
+    if (ptr == NULL || ptr != zlib_ver)
+        return false;
+
+    /* In zlib-ng, ZLIB_VERSION is of the form X.Y.Z.zlib-ng. This will move the
+     * pointer to the start of the suffix, .zlib-ng. We know that at this point
+     * that FOUND_ZLIB is the start of ZLIB_VERSION, so compare the rest.
+     */
+    ptr += strlen(found_zlib);
+    if (strcmp(ptr, ".zlib-ng") != 0)
+        return false;
+#else
+    if (strcmp(zlib_ver, found_zlib) != 0)
+        return false;
+#endif
+
+    return true;
+}
+
 int main(void) {
     void * something = deflate;
-    if(strcmp(ZLIB_VERSION, FOUND_ZLIB) != 0) {
+    if (!check_version(ZLIB_VERSION, FOUND_ZLIB)) {
         printf("Meson found '%s' but zlib is '%s'\n", FOUND_ZLIB, ZLIB_VERSION);
+#ifdef ZLIBNG_VERSION
+        puts("Note that in the case of zlib-ng, a version suffix of .zlib-ng is expected\n");
+#endif
         return 2;
     }
     if(something != 0)

test cases/linuxlike/13 cmake dependency/prog-checkver.c

@@ -1,11 +1,38 @@
 #include <zlib.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 
+static bool check_version(const char *zlib_ver, const char *found_zlib) {
+#ifdef ZLIBNG_VERSION
+    const char *ptr = strstr(zlib_ver, found_zlib);
+
+    // If the needle isn't found or the needle isn't at the start, fail.
+    if (ptr == NULL || ptr != zlib_ver)
+        return false;
+
+    /* In zlib-ng, ZLIB_VERSION is of the form X.Y.Z.zlib-ng. This will move the
+     * pointer to the start of the suffix, .zlib-ng. We know that at this point
+     * that FOUND_ZLIB is the start of ZLIB_VERSION, so compare the rest.
+     */
+    ptr += strlen(found_zlib);
+    if (strcmp(ptr, ".zlib-ng") != 0)
+        return false;
+#else
+    if (strcmp(zlib_ver, found_zlib) != 0)
+        return false;
+#endif
+
+    return true;
+}
+
 int main(void) {
     void * something = deflate;
-    if(strcmp(ZLIB_VERSION, FOUND_ZLIB) != 0) {
+    if (!check_version(ZLIB_VERSION, FOUND_ZLIB)) {
         printf("Meson found '%s' but zlib is '%s'\n", FOUND_ZLIB, ZLIB_VERSION);
+#ifdef ZLIBNG_VERSION
+        puts("Note that in the case of zlib-ng, a version suffix of .zlib-ng is expected\n");
+#endif
         return 2;
     }
     if(something != 0)