Also applies a fix for `spvOpcodeString` being moved to the public spirv-tools interface.

Changes:
    8910ea5f1 Fix Wrange-loop-analysis warnings in SPIRV-Tools. (#3201)
    c316fb15f Add missing dependencies when generating spvtools_core_tables (#3199)
    03c9effb5 Brief guide to writing a spirv-fuzz fuzzer pass (#3190)
    dea1040fa Fix ignored const qualifier warning in static_cast (#3197)
    4a80497a8 Make spvOpcodeString part of the public API (#3174)
    03794b8f5 Fix static libraries linking order (#3189)
    79f8caf91 vscode: Add missing fields to schema.Opcode (#3169)
    4d912f4e6 spirv-val: Add support for SPV_AMD_shader_image_load_store_lod (#3186)
    77fefe765 spirvfuzz: Fix type-related bug, change undef to zero, and add assert (#3188)
    6c218ec60 spirv-fuzz: Fuzzer pass that adds access chains (#3182)
    77fb303e5 spirv-fuzz: Fuzzer pass to add function calls (#3178)
    3d4a0dd48 spirv-fuzz: Ensure that donated variables are always initialized (#3181)
    fe10239f9 spirv-fuzz: Add fuzzer passes to add loads/stores (#3176)
    1f03ac102 spirv-fuzz: Fuzzer passes to add local and global variables (#3175)
    9e52bc0d0 utils/vscode: LSP - Support OpExtInst (#3140)
    a3b5ad909 Fix typos in opt's help. Update environment version. (#3170)
    da5457f6b Start SPIRV-Tools v2020.2
    8dd174809 Finalize SPIRV-Tools v2020.1
    76616bab6 Update CHANGES
    bb56e892f spirv-fuzz: Fuzzer pass to add composite types (#3171)
    fdd0c8776 Update script that checks copyright years. (#3173)
    b7e0998e3 spirv-fuzz: Disallow copying of null and undefined pointers (#3172)
    a9624b4d5 Handle TimeAMD in AmdExtensionToKhrPass. (#3168)
    ddcc11763 Update CHANGES
    0265a9d4d Implement constant folding for many transcendentals (#3166)
    7a2d408de Fix typo in comment. (#3163)
    1fc7a9ec7 spirv-fuzz: Arbitrary variable facts (#3165)
    dd3f8d492 spirv-fuzz: Add outlining test (#3164)
    521223b70 spirv-fuzz: Make functions "livesafe" during donation (#3146)
    97f1d485b Dead branch elim fix (#3160)
    1b3441036 Fix chromium build (#3152)
    5d786f6cc Clarify mapping of target env to SPIR-V version (#3150)
    e7afeb060 Use dummy switch instead of dummy loop in MergeReturn pass. (#3151)
    6729c4a7c Fix structured exit validation (#3141)
    bb236c326 Add spvParseVulkanEnv (#3142)
    dd37d73c5 Handle conflict between debug info and existing validation rule (#3104)
    b97057e7f Use spirv-headers' BUILD.gn (#3148)
    6a1a1b326 Roll external/spirv-headers/ af64a9e82..dc77030ac (4 commits) (#3147)
    ab7ac60f1 spirv-fuzz: Refactoring and type-related fixes (#3144)
    323a81fc5 Validate Vulkan 1.2 capabilities
    d46a1b048 Add basic support for Vulkan 1.2: SPV_ENV_VULKAN_1_2
    f8d7df760 Fix OpLine bug of merge-blocks pass (#3130)
    8013d477a spirv-fuzz: add dead blocks (#3135)
    18b3b9456 Remove names and decorations of imported symbols (#3081)
    fb2e81981 Fix GN build for OpenCL.DebugInfo.100 update (#3134)
    c86dc0bcd Fix bad parameter names in error message (#3129)
    899735f45 Revert PR #3093 (#3131)
    a466b99db Disallow forward references in arrays (#3093)
    31acc7882 spirv-fuzz: Add fuzzer pass to perform module donation (#3117)
    c8bf14393 GetOperandConstants operand can be const (#3126)

Commands:
    git subtree pull --prefix third_party/SPIRV-Tools https://github.com/KhronosGroup/SPIRV-Tools master --squash

Bug: b/123642959
Bug: angleproject:4425
Change-Id: I73076a22b474893d900a017d94a5d122061381bc