When SSE2 is not available on X86, make the CPU "unknown." This allows
the build to complete on those machines without SSE2.

https://bugs.gentoo.org/730044

diff --git a/Source/WTF/wtf/PlatformCPU.h b/Source/WTF/wtf/PlatformCPU.h
index 8aac1024..e12483a0 100644
--- a/Source/WTF/wtf/PlatformCPU.h
+++ b/Source/WTF/wtf/PlatformCPU.h
@@ -101,11 +101,16 @@
     || defined(_M_IX86)  \
     || defined(_X86_)    \
     || defined(__THW_INTEL)
-#define WTF_CPU_X86 1
-#define WTF_CPU_KNOWN 1
 
 #if defined(__SSE2__) || (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
+#define WTF_CPU_X86 1
 #define WTF_CPU_X86_SSE2 1
+
+/* According to Source/cmake/WebKitCompilerFlags.cmake, SSE2 support
+ * is required for x86 processors. It's probably overkill, but one way
+ * to rescue the build is to downgrade to WTF_CPU_UNKNOWN instead of
+ * X86 when SSE2 is missing. */
+#define WTF_CPU_KNOWN 1
 #endif
 
 #endif
diff --git a/Source/cmake/WebKitCommon.cmake b/Source/cmake/WebKitCommon.cmake
index 98ee788a..c826ae04 100644
--- a/Source/cmake/WebKitCommon.cmake
+++ b/Source/cmake/WebKitCommon.cmake
@@ -116,13 +116,7 @@ if (NOT HAS_RUN_WEBKIT_COMMON)
         # on a Linux/intel 64bit host. This allows us to produce 32bit
         # binaries without setting the build up as a crosscompilation,
         # which is the only way to modify CMAKE_SYSTEM_PROCESSOR.
-        if (FORCE_32BIT)
-            set(WTF_CPU_X86 1)
-        else ()
-            set(WTF_CPU_X86_64 1)
-        endif ()
-    elseif (LOWERCASE_CMAKE_SYSTEM_PROCESSOR MATCHES "(i[3-6]86|x86)")
-        set(WTF_CPU_X86 1)
+        set(WTF_CPU_X86_64 1)
     elseif (LOWERCASE_CMAKE_SYSTEM_PROCESSOR MATCHES "(ppc|powerpc)")
         set(WTF_CPU_PPC 1)
     elseif (LOWERCASE_CMAKE_SYSTEM_PROCESSOR MATCHES "ppc64")