Call posix_spawnp through a wrapper functions, since the nullability changed in incompatible ways between Android NDK r27 and r28

This will allow the package to build with both r27 and r28, the former of which is currently the default on swiftlang's GitHub Actions CI.

Author: jakepetroules

Sources/TSCBasic/Process/Process.swift

@@ -742,7 +742,7 @@ public final class Process {
         }
         let argv = CStringArray(resolvedArgs)
         let env = CStringArray(environment.map({ "\($0.0)=\($0.1)" }))
-        let rv = posix_spawnp(&processID, argv.cArray[0]!, &fileActions, &attributes, argv.cArray, env.cArray)
+        let rv = SPM_posix_spawnp(&processID, argv.cArray[0]!, &fileActions, &attributes, argv.cArray, env.cArray)
 
         guard rv == 0 else {
             throw SystemError.posix_spawn(rv, arguments)

Sources/TSCclibc/include/process.h

@@ -18,6 +18,8 @@ int SPM_posix_spawn_file_actions_addchdir_np(posix_spawn_file_actions_t *restric
 // Runtime check for the availability of posix_spawn_file_actions_addchdir_np. Returns 0 if the method is available, -1 if not.
 bool SPM_posix_spawn_file_actions_addchdir_np_supported();
 
+int SPM_posix_spawnp(pid_t *pid, const char *file, const posix_spawn_file_actions_t *actions, const posix_spawnattr_t *attr, char *const argv[], char *const env[]);
+
 #ifdef TSC_API_UNAVAILABLE_DEFINED
 #undef TSC_API_UNAVAILABLE_DEFINED
 #undef __API_UNAVAILABLE

Sources/TSCclibc/process.c

@@ -52,4 +52,8 @@ bool SPM_posix_spawn_file_actions_addchdir_np_supported() {
 #endif
 }
 
+int SPM_posix_spawnp(pid_t *pid, const char *file, const posix_spawn_file_actions_t *actions, const posix_spawnattr_t *attr, char *const argv[], char *const env[]) {
+    return posix_spawnp(pid, file, actions, attr, argv, env);
+}
+
 #endif