Add necessary defines and function prototypes for EXT_draw_buffers and multiple color attachment points to gl2ext.h.
Add necessary defines and function prototypes for EXT_draw_buffers and multiple color attachment points to gl2ext.h.

TRAC #22656

Signed-off-by: Nicolas Capens
Signed-off-by: Shannon Woods
Author: Jamie Madill

git-svn-id: 2a1ef23f1c4b6a1dbccd5f9514022461535c55c0@2003 736b8ea6-26fd-11df-bfd4-992fa37f6226

android-ia/platform_external_chromium_org_third_party_angle,cvsuser-chromium/chromium-third-party_angle_dx11,android-ia/platform_external_chromium_org_third_party_angle_dx11,themusicgod1/angleproject,xin3liang/platform_external_chromium_org_third_party_angle,cvsuser-chromium/chromium-third-party_angle_dx11,ehsan/angle,ehsan/angle,android-ia/platform_external_chromium_org_third_party_angle,shairai/angleproject,RepublicMaster/angleproject,themusicgod1/angleproject,xin3liang/platform_external_chromium_org_third_party_angle_dx11,cvsuser-chromium/chromium-third-party_angle_dx11,KTXSoftware/angleproject,stammen/angleproject,KTXSoftware/angleproject,MIPS/external-chromium_org-third_party-angle_dx11,shairai/angleproject,MIPS/external-chromium_org-third_party-angle,geekboxzone/lollipop_external_chromium_org_third_party_angle,MSOpenTech/angle-win8.0,geekboxzone/lollipop_external_chromium_org_third_party_angle,jgcaaprom/android_external_chromium_org_third_party_angle,vvuk/angle-old,RepublicMaster/angleproject,MSOpenTech/angle-win8.0,ehsan/angle,geekboxzone/lollipop_external_chromium_org_third_party_angle,vvuk/angle-old,RepublicMaster/angleproject,android-ia/platform_external_chromium_org_third_party_angle,jgcaaprom/android_external_chromium_org_third_party_angle,KTXSoftware/angleproject,KalebDark/angleproject,xuxiandi/angleproject,android-ia/platform_external_chromium_org_third_party_angle,cantren/angleproject,MSOpenTech/angle-win8.0,xin3liang/platform_external_chromium_org_third_party_angle,jgcaaprom/android_external_chromium_org_third_party_angle,xin3liang/platform_external_chromium_org_third_party_angle_dx11,MIPS/external-chromium_org-third_party-angle,KalebDark/angleproject,KalebDark/angleproject,xin3liang/platform_external_chromium_org_third_party_angle,MIPS/external-chromium_org-third_party-angle_dx11,MIPS/external-chromium_org-third_party-angle_dx11,xin3liang/platform_external_chromium_org_third_party_angle_dx11,geekboxzone/lollipop_external_chromium_org_third_party_angle,xuxiandi/angleproject,cantren/angleproject,shairai/angleproject,themusicgod1/angleproject,xuxiandi/angleproject,pombreda/angleproject,shairai/angleproject,xin3liang/platform_external_chromium_org_third_party_angle,android-ia/platform_external_chromium_org_third_party_angle_dx11,vvuk/angle-old,MIPS/external-chromium_org-third_party-angle,pombreda/angleproject,jgcaaprom/android_external_chromium_org_third_party_angle,MIPS/external-chromium_org-third_party-angle_dx11,cvsuser-chromium/chromium-third-party_angle_dx11,pombreda/angleproject,KalebDark/angleproject,KTXSoftware/angleproject,android-ia/platform_external_chromium_org_third_party_angle_dx11,vvuk/angle-old,KTXSoftware/angleproject,xuxiandi/angleproject,android-ia/platform_external_chromium_org_third_party_angle_dx11,RepublicMaster/angleproject,xin3liang/platform_external_chromium_org_third_party_angle_dx11,cantren/angleproject,stammen/angleproject,MSOpenTech/angle-win8.0,cantren/angleproject,stammen/angleproject,ehsan/angle,themusicgod1/angleproject,pombreda/angleproject,MIPS/external-chromium_org-third_party-angle,stammen/angleproject