Switch mkbootfs to C++.

Minimum changes just to get it to compile as C++, no real cleanup.

Change-Id: I8ff3fa35a07cdc9a6a246e79e33581e5d6598833
diff --git a/mkbootfs/Android.bp b/mkbootfs/Android.bp
index cd2a624..e0191f0 100644
--- a/mkbootfs/Android.bp
+++ b/mkbootfs/Android.bp
@@ -6,7 +6,7 @@
 
 cc_binary_host {
     name: "mkbootfs",
-    srcs: ["mkbootfs.c"],
+    srcs: ["mkbootfs.cpp"],
     cflags: ["-Werror"],
     static_libs: [
         "libbase",
diff --git a/mkbootfs/mkbootfs.c b/mkbootfs/mkbootfs.cpp
similarity index 96%
rename from mkbootfs/mkbootfs.c
rename to mkbootfs/mkbootfs.cpp
index 84a0a4e..65cf497 100644
--- a/mkbootfs/mkbootfs.c
+++ b/mkbootfs/mkbootfs.cpp
@@ -75,7 +75,7 @@
     }
 }
 
-static void _eject(struct stat *s, char *out, int olen, char *data, unsigned datasize)
+static void _eject(struct stat *s, const char *out, int olen, char *data, unsigned datasize)
 {
     // Nothing is special about this value, just picked something in the
     // approximate range that was being used already, and avoiding small
@@ -151,9 +151,10 @@
     DIR* d = opendir(in);
     if (d == NULL) err(1, "cannot open directory '%s'", in);
 
+    // TODO: switch to std::vector
     int size = 32;
     int entries = 0;
-    char** names = malloc(size * sizeof(char*));
+    char** names = (char**) malloc(size * sizeof(char*));
     if (names == NULL) {
       errx(1, "failed to allocate dir names array (size %d)", size);
     }
@@ -167,7 +168,7 @@
 
         if (entries >= size) {
           size *= 2;
-          names = realloc(names, size * sizeof(char*));
+          names = (char**) realloc(names, size * sizeof(char*));
           if (names == NULL) {
             errx(1, "failed to reallocate dir names array (size %d)", size);
           }
@@ -445,15 +446,12 @@
     int num_dirs = argc - optind;
     argv += optind;
 
-    while(num_dirs-- > 0){
+    while (num_dirs-- > 0){
         char *x = strchr(*argv, '=');
-        if(x != 0) {
-            *x++ = 0;
-        } else {
-            x = "";
+        if (x != nullptr) {
+            *x++ = '\0';
         }
-
-        archive(*argv, x);
+        archive(*argv, x ?: "");
 
         argv++;
     }