Make sure to add the actual location of the headers to the search path.

It is beyond me how some Xcode configurations have ever been able to build
without this. Gotta love it.

lib/cocoapods/installer.rb

@@ -33,8 +33,9 @@ module Pod
 
     def xcconfig
       @xcconfig ||= Xcode::Config.new({
-        # in a workspace this is where the static library headers should be found
-        'USER_HEADER_SEARCH_PATHS' => '$(BUILT_PRODUCTS_DIR)',
+        # In a workspace this is where the static library headers should be found
+        # We could also make this recursive, but let's let the user decide on that.
+        'USER_HEADER_SEARCH_PATHS' => '$(BUILT_PRODUCTS_DIR)/Pods',
         # search the user headers
         'ALWAYS_SEARCH_USER_PATHS' => 'YES',
       })

spec/unit/installer_spec.rb

@@ -19,7 +19,7 @@ describe "Pod::Installer" do
         ['Classes'],
         "{Classes,External/Reachability}/*.{h,m}",
         {
-          "USER_HEADER_SEARCH_PATHS" => "$(BUILT_PRODUCTS_DIR)",
+          "USER_HEADER_SEARCH_PATHS" => "$(BUILT_PRODUCTS_DIR)/Pods",
           "ALWAYS_SEARCH_USER_PATHS" => "YES",
           "OTHER_LDFLAGS" => "-framework SystemConfiguration -framework CFNetwork " \
                              "-framework MobileCoreServices -l z.1.2.3"
@@ -30,7 +30,7 @@ describe "Pod::Installer" do
         ["External/Reachability/*.h", "External/Reachability/*.m"],
         "External/Reachability/*.{h,m}",
         {
-          "USER_HEADER_SEARCH_PATHS" => "$(BUILT_PRODUCTS_DIR)",
+          "USER_HEADER_SEARCH_PATHS" => "$(BUILT_PRODUCTS_DIR)/Pods",
           "ALWAYS_SEARCH_USER_PATHS" => "YES"
         }
       ],
@@ -39,7 +39,7 @@ describe "Pod::Installer" do
         ['**/ASIWebPageRequest.*'],
         "{Classes,Classes/ASIWebPageRequest,External/Reachability}/*.{h,m}",
         {
-          "USER_HEADER_SEARCH_PATHS" => "$(BUILT_PRODUCTS_DIR)",
+          "USER_HEADER_SEARCH_PATHS" => "$(BUILT_PRODUCTS_DIR)/Pods",
           "ALWAYS_SEARCH_USER_PATHS" => "YES",
           "HEADER_SEARCH_PATHS" => "$(SDKROOT)/usr/include/libxml2",
           "OTHER_LDFLAGS" => "-l xml2.2.7.3 -framework SystemConfiguration " \