Small changes to get things building and running on Linux/ARM.

ninja -C out/Debug works, and I tested out/Debug/dm --nogpu (no X yet).

The only problems encountered were:
  - Like CrOS, I also needed to use the default float ABI (presumably hard).
  - The strings in GrBinHashKeyTest weren't necessarily 4-byte aligned.

BUG=skia:

Review URL: https://codereview.chromium.org/746043002

gyp/common_conditions.gypi

@@ -298,7 +298,7 @@
                   'SK_ARM_HAS_OPTIONAL_NEON',
                 ],
               }],
-              [ 'skia_os != "chromeos"', {
+              [ 'skia_os != "chromeos" and skia_os != "linux"', {
                 'cflags': [
                   '-mfloat-abi=softfp',
                 ],

tests/GrBinHashKeyTest.cpp

@@ -13,11 +13,17 @@
 
 #include "Test.h"
 
+struct AlignedKey {
+    uint32_t align;
+    char key[8];
+};
+
 template<typename KeyType> static void TestHash(skiatest::Reporter* reporter) {
-    const char* testStringA_ = "abcdABCD";
-    const char* testStringB_ = "abcdBBCD";
-    const uint32_t* testStringA = reinterpret_cast<const uint32_t*>(testStringA_);
-    const uint32_t* testStringB = reinterpret_cast<const uint32_t*>(testStringB_);
+    AlignedKey a, b;
+    memcpy(&a.key, "abcdABCD", 8);
+    memcpy(&b.key, "abcdBBCD", 8);
+    const uint32_t* testStringA = reinterpret_cast<const uint32_t*>(&a.key);
+    const uint32_t* testStringB = reinterpret_cast<const uint32_t*>(&b.key);
 
     KeyType keyA;
     keyA.setKeyData(testStringA);