edify extensions for OTA package installation, part 2

Adds more edify functions for OTAs:

  is_mounted getprop apply_patch apply_patch_check apply_patch_space
  write_raw_image write_firmware_image package_extract_file

This allows us to install radios, hboots, boot images, and install
incremental OTA packages.

Fixes a couple of dumb bugs in edify itself:

  - we were doubling the size of the function table each time it was
    *not* full, rather than each time it was full

  - "no such function" errors weren't visible to the parser, so they
    didn't prevent execution of the script.
diff --git a/edify/expr.c b/edify/expr.c
index 129fbd9..5470a2b 100644
--- a/edify/expr.c
+++ b/edify/expr.c
@@ -283,7 +283,7 @@
 NamedFunction* fn_table = NULL;
 
 void RegisterFunction(const char* name, Function fn) {
-  if (fn_entries <= fn_size) {
+  if (fn_entries >= fn_size) {
     fn_size = fn_size*2 + 1;
     fn_table = realloc(fn_table, fn_size * sizeof(NamedFunction));
   }
diff --git a/edify/main.c b/edify/main.c
index c959683..7da89e2 100644
--- a/edify/main.c
+++ b/edify/main.c
@@ -153,10 +153,11 @@
   buffer[size] = '\0';
 
   Expr* root;
+  int error_count = 0;
   yy_scan_bytes(buffer, size);
-  int error = yyparse(&root);
-  printf("parse returned %d\n", error);
-  if (error == 0) {
+  int error = yyparse(&root, &error_count);
+  printf("parse returned %d; %d errors encountered\n", error, error_count);
+  if (error == 0 || error_count > 0) {
     char* result = Evaluate(NULL, root);
     if (result == NULL) {
       char* errmsg = GetError();
diff --git a/edify/parser.y b/edify/parser.y
index 67a210f..cf163c0 100644
--- a/edify/parser.y
+++ b/edify/parser.y
@@ -25,8 +25,8 @@
 extern int gLine;
 extern int gColumn;
 
-void yyerror(Expr** root, const char* s);
-int yyparse(Expr** root);
+void yyerror(Expr** root, int* error_count, const char* s);
+int yyparse(Expr** root, int* error_count);
 
 %}
 
@@ -45,6 +45,7 @@
 %type <args> arglist
 
 %parse-param {Expr** root}
+%parse-param {int* error_count}
 %error-verbose
 
 /* declarations in increasing order of precedence */
@@ -86,7 +87,7 @@
     if ($$->fn == NULL) {
         char buffer[256];
         snprintf(buffer, sizeof(buffer), "unknown function \"%s\"", $1);
-        yyerror(root, buffer);
+        yyerror(root, error_count, buffer);
         YYERROR;
     }
     $$->name = $1;
@@ -113,9 +114,10 @@
 
 %%
 
-void yyerror(Expr** root, const char* s) {
+void yyerror(Expr** root, int* error_count, const char* s) {
   if (strlen(s) == 0) {
     s = "syntax error";
   }
   printf("line %d col %d: %s\n", gLine, gColumn, s);
+  ++*error_count;
 }